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Fine-tuning the Swing Based Upon Statcast Data

In this article I have researched the relationship between Batted ball direction and production. I found out that air balls are more effective if they are pulled than hit to center but especially hit the other way. That can be already seen on liners a little bit but especially on fly balls which are very dependent on batted ball direction.

However the downside is that pulling actually suppresses LA, especially low in the zone because you will roll over and topspin more balls when you try to pull them. I broke this down in this table LA by hit direction and zone

This shows that you can only pull certain pitches consistently unless you have a special talent. Generally the more down and away the harder to pull it off the ground and the more up and in the easier.

In this article I showed that most top hitters average around 12-18 degrees. That is interesting because the most productive LAs are around 25 degrees if struck perfectly. However this is only true if you strike the ball perfectly and also while batted balls are distributed more like a bell curve (looks different because it is a cumulative curve) around the median as Tom Tango shows here batted ball distribution the production really isn’t as production increases on a slower slope towards 30 degrees than it drops off after it. That means you want to shift more batted balls into that good 10-30 window even if this means losing some of the great 25-30 balls.

And also ideal production in relation to LA is not the same depending on batted ball direction.
production based on direction . You can see that pulled balls have the highest wOBA at 20-35 degrees, balls to center are best at 10-25 and oppo best at 5-20. Unfortunately the batted ball trend is exactly vice versa, as the LA on pulled balls is only around 5 degrees for the league vs 20 for oppo. That means you don’t need to spend much effort on lifting oppo balls as well as high pitches

The goal of a hitter should be finding pitch locations that he can pull in the air which is also highlighted in the above linked article. Also the hitter should avoid rolling over into grounders by not pulling balls that he can’t pull (by either taking them or hitting them to other fields) and lastly he should try to avoid too high LAs on balls hit the other way.

But priority is clearly first to avoid the grounder, especially to the pull side as this ist he worst batted ball type, then secondly to try to pull the air ball (but this comes clearly second to avoiding the grounder) and lastly there is avoiding high LAs on oppo balls.

For this I suggested this chart in my prior article optimized batted ball direction by zone. It suggests to pull inside pitches and also high middle pitches which are easy to lift. It also suggests that low middle pitches are hit up the middle to get them off the ground and unsurprisingly low and away pitches hit the other way. This is pretty much conventional wisdom except turning on the high middle pitch. Where my optimized approach differs from „hitting where it is pitched“ is that it suggests hitting higher (and middle high) outside balls more up the middle or maybe very slightly to oppo than really to the outer third of the field. This is to push the LA down a little from the 25 degrees that high outside pitches hit to oppo yield.

To summarize this so far we have:

*Hit the ball where it is pitched except for the high middle pitch that should be hooked to pull field and the high outside pitch which should be hit more middle to oppo gap rather than straight oppo.

*Try to shrink the zone a little on the low outside (bad launch angle and absolutely not pull-able) and very up and in pitches (suppresses EV and could cause pop ups and whiffs).

*Ff you are a pull/FB hitter try to polarize your swinging a little toward the zones in which you can elevate to pull field.

Of course there is more to it. Some guys like Bautista made a living out of pulling balls in the air and other guys like Trout or JD Martinez are able to pull the ball but actually have slightly below average pull rates and have mentioned that their default approach is fastball center to oppo gap and then react in on inside pitches and some off-speed stuff. This has advantages too since the little deeper FB contact means you have a little more room out front if you are fooled on the breaking stuff. This approach sacrifices a little bit of power but maybe prevents more rolled over grounders, helps BABIP a little and of course Trout and JDM are strong enough to hit it out to the middle oft he field.

In contrast to that hitters like Brian Dozier need to pull the ball to do damage in the air. Dozier with his extreme pull/FB approach thus gets more out of his raw power than Trout and JDM but he does pay a BABIP price because he does polarize his z-swing Dozier heat map but still will pull some non pull-able pitches leading to pulled grounders despite his overall low GB rate.

The Effect of Batted-Ball Direction on Launch Angle

Fortunately Statcast now has a function that allows to sort for batted ball direction. This opens the chance for some new studies. Until now we just had launch angle (LA) and exit velocity (EV), however, that is not quite perfect because we already new that it is easier to pull fly balls for power. This was known intuitively for a long time but was hard to quantify until now.

One of the effects is certainly that parks are bigger in center field than they are down either line. However I also looked at EV and average distance of balls pulled, hit to center and oppo at angles of 20-35 degrees which are typical HR angles. For this article I only looked at right handed hitters, -45 to -15 was defined as pull, -15 to 15 as center center and 15 to 45 degrees as oppo.

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You can see that pulled balls yield a 343 ft distance and 92.4 EV. To center it is slightly lower (91.4/338) but to opposite field it drops dramatically to 290/86.2. From a physics standpoint that makes sense because the contact on inside pitches is supposed to be further out front so that the swing is slightly longer and thus has more time to accelerate to contact which probably means more bat-speed at impact.

wOBA supports this, while liners are relatively stable in production, the wOBA of pulled fly balls is dramatically higher. On grounders this trend is reversed and oppo grounders are better than pulled grounders.

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I also looked at the top and bottom 20 of the league in pull and oppo LA:

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You can see that pull LA has a pronounced positive effect while oppo LA even has a slightly negative effect. It might make sense to try to lift more on pulled balls and slightly try to suppress LA (“get on top”) on oppo hit balls. Not sure if this is possible with the same swing though, I think usually the guys having a high FB pull rate also have high grounder pull rates because that is the natural tendency of the swing.

So it seems to be pretty simple: pull the ball in the air and be productive.

However it isn’t quite as simple. Already before Statcast it was known that pulled balls are hit on the ground at a much higher frequency

Launch angle supports that, pulled balls last year had an average LA of 5.6 degrees vs 13.1 for balls up the middle and 20 degrees oppo.

This makes sense and actually is something that isn’t easily combatted with the modern swing. The modern swing goes slightly up and pulled balls are hit out front. You can lift a ball like this but if you are a little too far out front the bat has risen above the plane of the pitch which means you hit the top of the ball and roll over hitting a hard topspin grounder, often into the shift.

This is especially pronounced on low pitches.

There are some hitters who have developed a tool to combat that rolling over with the uppercut swing as I have shown in this article by using a steeper bat angle but it is not easy to do as the league still tends to have much lower launch angles on low and especially away pitches

I broke this down a little more looking at batted ball directions and pitch locations inside the zone

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You can see that low pitches that are pulled are especially hard to lift, most extreme is that on low and away pitches but even the down and in pitch only yields a modest 6 degree LA.

I also looked at pulled balls above 10 degrees on low pitches. The leaders in that stat were in this order Stanton, Machado, Salvador Perez, Hunter Renfroe, Nelson Cruz and Mookie Betts. Those were some pretty good hitters last year, so maybe that is a skill that deserves further examination.

We all have seen Bryce Harper pull outside pitches for a homer and it does happen but generally trying to pull anything away is not a good receipt. If it works it usually is on pitches up (still yields a positive 7 degree LA to pull up and away pitches).

An adjustment that might make sense is trying to hit up and away and middle away balls to center rather than the other way. That way you could bring down the average EV of those pitches from a too-high-upper-20s average EV to a better low 20s EV, which yields a better BABIP on those pitches which tend to yield lower EVs. I elaborated in this article why mid-20s LAs are ideal but actually average LAs should be lower (between like 12 and 18 or so)

Overall an LA optimizing strategy using batted ball direction could look like this.

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So pulling the ball is good but only if you have the skill to put it in the air. Selecting the right pitches to do it certainly helps. On pitches that are low and away it still makes sense to follow the old advice to hit it were it is pitched. And for pitchers it might make sense to work the outside corner more, however that is also a fine line since you need to prevent the old Jose Bautista strategy of creeping closer to the plate and turning the outside pitch into a middle pitch. For this you need to pitch inside some to keep the hitters honest.

Finding Keys to Elevate the Ball More

Everyone is looking for keys to get players to elevate the ball. One important point is certainly the so called attack angle. The attack angle is the angle of which the bat attacks the ball (uppercut, level or down). Baseball used to teach swinging down but now you actually want a small uppercut. Players use different cues to achieve that. Common cues are for example leaning slightly back to the catcher and work up with the front elbow.

Up in the zone elevating is pretty easy. The league average launch angle (LA) in the upper third of the zone is 20 degrees. Even Christian Yelich averages 15 degrees in the upper part oft the zone. In a prior analysis I also found out that LA in the upper part of the zone has little influence on wOBA, the 20 lowest average LA guys in the upper third actually had a slightly better wOBA than the 20 highest LA guys (.402 vs .393). 170 out of 182 hitters last year averaged 10-plus degrees.

That is very different low in the zone. The league average LA in the lower third was just 5 degrees and over 30 guys actually had a negative LA. Here the wOBA for the high LA guys is 80 points higher than the low LA guys. The difference is made low in the zone.

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So the key for the low LA guys is definitely still to lift the low pitch. So how can this be achieved? You definitely need to swing up and you also need to avoid rolling over and hitting a grounder to pull field which is what the sinker-ballers try to achieve.

One theory is that on low pitches you tilt the shoulders more down and hit with the bat pointing more to the ground. The cue is that for high pitches the bat turns more like a merry go round and on low pitches more like a ferris wheel.

This Ferris Wheel like path makes sure that the bat comes through more straight through from below rather than going across the ball which leads to rolling over.

Mike Trout is so good at this that he is able to sometimes even hit down and in pitches  to dead center for a bomb while most have to pull that ball. Jeff wrote a nice article about this:

Of course this Ferris Wheel path also has his disadvantages, for example Trout used to be very bad on high pitches the first 4 years of his career. Still he got away with that because most pitchers would only pitch up like once per at bat and not live up in the zone so Trout would just take but ideally a batter would flatten out the bat up in the zone and swing steeper down which Trout actually did last year causing him to improve up.

But the traditional level bat, level shoulders cue is definitely hurting on low pitches and made the sinker so popular. Now that more guys learn the new swing path the sinker doesn’t work as well anymore but there are still hitters who struggle down (like Hosmer and Yelich).

The pitch up is getting more popular but it can not suppress launch angle. The high pitch lifts itself, when a pitcher pitches up he needs to compensate for the higher LA by more pop ups, lower EV and more Ks.

It is a good sign that Hosmer now thinks about swinging up more but if he wants to increase his LA he either needs to stop swinging at pitches in the lower third and target pitches up or change the rotation axis of his bat to more vertical on top of his attack angle because if you swing up but across the ball on low pitches all you do is hitting your grounders with more topspin.

I measured the vertical angle of some good and bad low ball hitters. On the left of the picture you have Yelich and Hosmer and the other pics are Ortiz, Trout and Votto who are all excellent low ball hitters. All pitches I chose were about knee high and on the inside of the plate because that affects the bat angle.

What you can see is that Hosmer and Yelich have an angle in the mid 20s while the other three are in the low to mid 40s.

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That is important because on low pitches the flat barrel will naturally rotate to the left causing top spin similar to a tennis top spin while the steep barrel will rotate up and on the line to CF.

So to learn to elevate getting a positive attack angle by leaning slightly back and keeping the head over the rear hip during the turn and working the front elbow slightly up definitely is important, but you also need to match the rotation axis of the bat around its long axis with the height of the pitch. The old cue of not dropping the back shoulder and hit with a level bat has its merits on pitches above the waist where a too steep bat angle is indeed bad (see young Trout) but on pitches mid-thigh to knee height this cue is very destructive. In the upper third of the zone the bat angle will be relatively flat ,but in the lower third you need to drop the back shoulder and tilt the rotation axis oft he bat down to around 40-45 degrees.

That means changing the swing isn’t that easy, you have to account for several things. It can be done but it is some work, will we see Hosmer and Yelich making all those adjustments? If they don’t make it they could also adjust less and try to just avoid hitting the low pitch but of course, that would eventually give the pitchers an opening to exploit.

So far there is no improvement for Hosmer. It is early but his GB rate is 58%. He either needs to stay away from the low pitches and target pitches up (and away in his case) or make more changes to his swing.

Is the Second Wild Card the Problem?

I have wondered about this. Unlike my other articles this is going to be less analytical so don’t be mad at me and maybe discuss in the comments. There is a lot of talk about why middle ground teams are not investing to get better.

Now, of course, competitive baseball is better but we also can’t expect teams to fight a futile fight. We do now have better projections, aging curves and other stuff and we can’t teams to just act like this didn’t exist. Winning should be the goal but throwing away the future doesn’t make sense either.

In theory, the second Wild Card is another playoff spot but in reality, it is really only half a playoff spot. There is value in the Wild Card but teams are not really attacking it preseason, they will wait and see and then maybe make a small deadline move. It really isn’t worth to throw away the future for a 30% or so chance of reaching a coinflip game if you are a .500 team.

The second Wild Card has mostly hurt the first Wild Card team and it has increased the incentive to be a super team especially in a weak division. IMO,  being a super team is too big of an advantage because there is also less risk to being in being kicked out by a weakened Wild Card team that has used its ace in a one-game playoff.  And at the same time there is too little reward for being the fourth best team.

That means teams either try to tank to become a super team or they try to stay a boring .500 team doing not much hoping to occasionally luck into a Wild Card like the pirates might want to do now.

We can’t just force teams to spend money foolishly, if we want teams to spend more and try to be competitive we need to actually increase the incentive to win as a non super teams and maybe also punish the super teams with a little more variance.

Now of course not anyone wants that. Some like the best team to win and baseball already has some of the more luck influenced playoffs but if you want teams to compete you need to change the rules.

One possibility would be doing away with the second Wild Card so that being the Wild Card really guarantees a playoff spot. Another thing you could do is doing away with the divisions and make it top 4 per league directly to the playoffs or maybe even use NBA-style 16 team playoffs (although that would be too much variance for me).

IMO we shouldn’t talk so much about punishing bad teams but about making good not great more lucrative. Currently, 2/3rd of each league just have little inventive to be buyers because the super teams have too much of an edge and the second Wild Card might have increased that division.

The second Wild Card was a good idea but teams have really voted with their feet and decided the second Wild Card is not a full playoff spot and thus not worth chasing with a lot of resources.

Effect of Pitch Selection on Launch Angle and Exit Velocity

When talking about launch angle much focus is on swing plane and of course rightfully so. Many players like Jose Bautista, Josh Donaldson, Daniel Murphy and Justin Turner have demonstrated that it is possible to change the swing and achieve spectacular gains in power output.

However also the plate discipline by the hitter and the way he is pitched have an effect. Looking at Statcast data the average launch angle in the upper third oft he zone is around 20 degrees, while it is only 5 degrees in the lower third. Of course that doesn’t mean higher pitches are better to swing at, high pitches are also known to induce more pop-ups and whiffs on certain types of fastballs (high spin) but for players who have trouble to elevate the ball it can make sense to swing a little less in the lower part of the zone. On the other hand a high whiff or popup rate type of player who has a good launch angle it might make sense to leave the high pitches alone.

I did a breakdown of the zones for right-handed hitters. I looked for LA but also exit velocity to see where the good parts are. Unsurprisingly pitches over the plate do better in both LA and EV. Inside pitches did better in the LA but worse in the EV and for outside pitches it was vice versa, better LA but worse LA.

Just high and low both did about the same in EV but high did better in LA by far. When looking finer we could confirm that the combination of low and away gave the lowest launch angles and up and in gave the highest, but up and in also by far yielded the worst exit velocities probably because there is the least space to get the barrel around up and tight – so there is a trade-off between EV and LA.

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Over the plate is, of course, good and middle pitches too as are up and away and down and in. The down-away to up-and-in axis is probably to avoid.So ideally a batter would have a slightly tilted away from him zone (imagine the zone is a rectangle piece of wood and the batter pushes the top of the piece away from him so that the top is farther away from him than the bottom. Also it should be a little wider in the middle than in the very edges (like an ellipse)


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Of course, the pitcher has a say in this too. If a hitter adjusts pitchers will adjust too. There are some batters who can beat that a little like for example Brian Dozier who is very quick to the inside and thus can crowd the plate a little without opening apart but for most hitters that is not really true. So if a batter has a swing change and then struggles in the second half we should probably also look at the swing and pitch profile. Still, it is good for a hitter to match his swing rates and hot zones as even good pitchers will miss their target quite a few times. A batter not aware of his hot zones could leave serious potential on the table.

I also found one interesting thing. I looked at right-handed batters mostly in my analysis but also did a quick check on lefties. The lefties had a higher LA on inside pitches than the righties but a lower one than the righties on outside pitches? Why is that? handedness of pitchers faced maybe? I found indeed that righties facing opposite-handed pitchers indeed have a higher LA on inside pitches than against same-sided pitchers and against LHPs it was vice versa, so there seems to be an effect there.

And, lastly, the LA on offspeed pitches (10 degrees) was slightly lower than on fastballs (11 degrees). Surprisingly low breaking balls had a higher LA than low FBs but inside OS pitches where easier to lift.

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The Pirates and the Value of Being Around .500

I was at first very critical of the Pirates trades. I didn’t think the surplus value is bad, but I didn’t like getting older prospects with lower ceilings who are MLB-ready instead of higher-upside guys who are farther away. My thinking was that the Pirates can’t buy upside, and while those good depth pieces help them to stay around .500, they don’t make them a great team. However, what if that is what the Pirates want? I thought it might make sense to tank completely and rebuild for a couple years, but maybe there is value to being an average team in the two-WC era.

So first I looked at what is needed to win a WC.

Year NL AL
2017 87 85
2016 87 89
2015 97 86
2014 88 88
2013 90 92
AVG 89.8 88

So roughly 88 wins are needed, and you have a chance with 85+.

I compared last year’s projections (average of PECOTA and FG) with the actual results and calculated the absolute distance (eliminating negative numbers to make the math easier) and the difference (found the projections here).

The average difference to the projection was 7.1 wins. Those differences don’t mean projections are bad; there is always under and overperformance, unlikely breakouts as well as injuries. Also just Pythagoran luck or bad luck can easily make up 3-4 wins or more. Of course this goes both ways — an 81-win team can easily have a 71-win season, but there definitely is a chance.

As you can see in the upper graphic, usually around 88-89 wins get you a WC, although you sometimes can get one with 85 or sometimes 90+ is required. So a .500 team needs to make up like seven games to get into the postseason. With a little bit of overperformance, one or two Pythagoran luck wins and one or two wins picked up in deadline trades, that is quite possible. Actually 30% of the MLB teams last year were plus-7 or better. That means a .500 team might have around a 30% chance to get (actually half) a playoff spot. That isn’t great, but if you are a .500 team for six years, that would mean two WC game appearances.

Now of course that is not ideal. Ideally you want a talent-oozing rebuild like the Cubs, White Sox, or Braves. But other teams now also have recognized the value of cheap controllable talent, and are much stingier with their top prospects. Also, currently many .500 teams have given up and prefer to start a rebuild or at least do nothing. That means, if anything, it might become a little easier to make a WC, because the emergence of the super teams might cause the in-between teams to push the reset button to become the next Cubs or Astros.

Maybe that is really what the Pirates were thinking. The Dave Stewarts are gone, and usually those plus 50M surplus-value trades that made rebuilding so attractive don’t happen anymore. Now you have to fight for every million of surplus value, as any intern or even hobby sabermetrist can easily get a pretty good guess of the surplus value of a trade. So maybe the Pirates are trying to use a little game theory here and go against the trend to try finding a market inefficiency. It is a little like with poker. If you play beginner levels, you don’t need to worry about game theory and out-thinking the opponent — you just play the plus-EV hands, occasionally make a bluff to keep them off balance, and then you win. But at higher levels, everyone plays the correct hands, and game theory and out-thinking the opponent like a chess player becomes more important. The early sabermetric age was a bit like beginner-level poker, and you just needed to make mathematically correct calls because enough Dave Stewarts were feeding you. But now there isn’t that much difference between analytical departments, so that for smaller-market teams, even less than optimal plays can become profitable if they catch the market off balance. A team like the Dodgers doesn’t need to do that; they just need to play the mathematically correct hand and avoid mistakes to let their resources do the work, as they just start with pocket aces more often.

But a cash-constrained team like the Pirates might need to do more to out-think opponents and go against the trend, because they can’t do what anyone else does with half the resources and expect to beat them. Sure, they would have preferred a GM giving them a Shelby Miller trade, but it just wasn’t available, so maybe they re-evaluated and chose a path of sustained mediocrity to chase the second WC.

The Pirates version isn’t sexy, just like the 2000s A’s way wasn’t sexy. People love to dream. They don’t want the bird in the hand — they want the two in the bush. Fans don’t want an outlook of “we can be an 83-win team for a couple years and maybe make a WC or two,” they want to dream about becoming the next juggernaut. Fans are extremely emotional about their prospects. They want to believe anyone is the next Babe Ruth and getting a couple of 25-year-old prospects doesn’t really elicit that dream. The Pirates fans don’t want that — they want to be the White Sox and have all those studs coming up. But then again, that is no guarantee, as just one or two years ago they had those studs themselves in Glasnow and Meadows and it didn’t work out that well (for now, of course — they could still break out).

At first I hated the trades, but maybe it is good that a team chose to actually value mid-80s wins rather than tanking like anyone else. Sure, it isn’t nice that their owner has tight pockets, and you would have wished for more, but a future where we just have super teams and tankers is really boring. Maybe that tanking hype is already self-correcting currently. Anyone might’ve wanted to be the next Cubs, but as more try it and at the same time the buyers get stingier with their prospects, that becomes increasingly harder to do, and maybe as a consequence teams start to value those half-playoff spots more. Baseball really needs a middle field or the regular season will become a long and boring spring training for the postseason (which admittedly has become really great with all those super teams).

Summarizing My Findings on Launch Angle

Over the last year I made a series of studies on Statcast and I thought it would be interesting to write a little overview article to summarize my findings.

In June I looked at the launch angle profile of the league. The average went up of course, but it accelerated faster at the top than at the bottom, so we have not reached a stage of consolidation yet where the league is moving closer together in launch angle, which ultimately should be expected (the LA is increasing at the bottom but less than at the top.

That means there still is room for more growth in elevating but mostly in the bottom half of launch angle.

In the above I found that there are limits to elevating. I found the top guys usually average 11-16 degrees of launch angle. Below that players definitely can benefit from elevating more.

Then I was looking at the cost of too much elevation. A common theory is that swinging up more leads to more Ks because you are not really matching the plane of the pitch. I found a small effect there but nothing really big.

However I did find that there is a BABIP cost, especially if it comes with pulling the ball, and confirmed that with more research and found out that elevating more without a BABIP cost is possible if you get off the ground while limiting pop-ups and high outfield FBs above 30 degrees like Daniel Murphy does very well, while the 50+% FB guys with 20+ degrees of average LA tend to have low BABIPs, especially when coupled with pulling a lot to sell out for power.

I also looked at the relationship of EV and LA and unsurprisingly found out that between like 8 and 20 degrees, exit velo doesn’t matter much, while above 20 degrees almost all production comes from homers. Balls above 20 degrees and below 95 MPH are basically worthless so you need a certain minimum power to make elevation work. Off the ground is always good, but for some it might make sense to stay between 5 and 20 degrees.

Not quite related to that topic, I also created a formula for the relationship between power, patience, and K rate. An old argument between sabermetric and traditional writers was whether Ks matter. We know that Ks are not worse than other outs and high-K hitters do not perform worse, but that is also because there is a selection bias against high-K, low-power guys. Everything being equal, low Ks is better, and I found a pretty linear relationship between K, BB, and ISO.

If production is equal, Ks obviously don’t matter, of course.

The Home Run Explosion, Home Runs, and Winning

I wondered how the power revolution changes the impact of power on winning. Does the abundance of HR mean that HRs are less valuable? Or are they even more necessary?

For that I compared 2017 and 2008. 2008 is kind of an arbitrary cutoff; I used it because it was 10 seasons ago and not a completely different game.

In 2008 the top-10 HR-hitting teams averaged 86 wins, and in 2017 just 82 wins. Also in the top 10 in HRs in 2008, three teams had losing seasons, and in 2017 it was a whopping five teams. So it seems being a top-HR team helps less.

However, when looking at the bottom 10 HR-hitting teams, it is 74 wins for both years. Three teams of the bottom 10 in HRs had winning seasons in 2008 versus just two in 2017. So it didn’t become easier to succeed as a no-power team.

The league also got closer together in HRs. In 2008 the bottom-10 average was 127, and it as 1.6 times as much for the top 10 (197). In 2017 it was 172 for the bottom and just 1.3 times as much for the top (230).

Of course park factors and year-to-year variations play a role, but last season Colorado wasn’t even in the top 10 for example.

So it seems power is at least as much needed to win as it used to be, but it isn’t really much of a difference maker anymore, it is more a baseline needed to win. But teams like the Rays and A’s who hit tons of homers in a pitcher’s park show that you can’t really build around power as a main skill; you need to make sure you don’t suck at power, but since you can’t really separate anymore with power, you need other primary skills.

I would probably say make sure to be in the top third in power, but once you are there, don’t sacrifice other stuff to get even more power.

That is especially true for defense. The A’s led the league in average launch angle and were fourth in HRs. Since they were only seven HR behind the Yankees and four behind the Astros in a vastly less hitter-friendly park, we can probably say they were the top HR-hitting team.

They tried to sell out for power and it clearly wasn’t enough to make up for historically bad defense and other flaws.

So teams definitely shouldn’t sacrifice in other regards; there is enough power around to not put bad defenders or super low OBPs in the field to get more power.

Power is as important as it ever, was but it is not possible to dominate with it anymore like the 1927 Yankees did. Now it is now one necessary skill of many and well-roundedness is the name of the game in 2017. Same can be said for contact-hitting. People said after 2015 that contact was the future. However, low-power slap hitting didn’t prove to be successful, but with power now available so easy, teams now might be able to cut back on the Ks a little without sacrificing power like the Astros did, because super high Ks can suppress on-base percentage when it doesn’t come with Adam Dunn-like walks.

Does Lifting the Ball Have a Ceiling?

Elevating is en vogue; everyone wants to do it and it seems like every hitter who does it can become a power hitter, especially with rumors about a new ball. There have been many examples of successful hitters of that mold: Daniel Murphy, Justin Turner and Jose Altuve, among others. Is there a limit to this? Could we see hitters with a 25% GB rate in the future? 20% 15%?

One thing that seems to cap this is BABIP. There is a pretty positive correlation of BABIP and GB rate, i.e. GB hitters tend to have a higher BABIP. That seems logical since FBs tend to have a lower average, and even if they are hits they often don’t count for BABIP as they are often home runs.

This table shows the relation of BABIP and GB rate between 2008 and 2017. You can see that BABIP does go down with lower GB rates, but wRC+ is actually better with lower GB rates. Still, you could see a point being reached where the lower BABIP eats up the advantages.

GB rate >0.35 0.35-0.4 0.4-0.45 0.45-0.5 0.5-0-55 >0.55
BABIP 0.287 0.290 0.299 0.304 0.314 0.320
wRC+ 106 102 101 95 90 93

Average launch angle shows a similar picture:


av. LA <8 8 to 10 10 to 12 12 to 14 14 to 16 16 to 18 >18
BABIP 0.318 0.314 0.305 0.298 0.300 0.289 0.274

It seems that once you get past a certain launch angle or GB rate, a drop in BABIP is inevitable. However, an exception might be possible. I looked up guys with a lower than 35% GB rate and a FB rate of lower than 45%, and their BABIP was 0.304. Those guys were pretty rare between 2008 and 2017, but it is possible. You just need to get the ball off the ground and avoid both pop-ups and high outfield fly balls above 25 degrees. Not an easy thing to do, though, as the bat is a round object, and batted balls will always be distributed rather normally around the average LA, meaning that a higher average LA usually will mean more high outfield fly balls.

However, it is possible to imagine a super-hitter who has such good bat control that his band is very narrow. The best example of this might be Daniel Murphy, who managed to have a 34% GB rate with just a 40% FB rate (meaning a very high LD rate), and subsequently a very high (.345) BABIP over the last three years.

So we could indeed imagine a kind of “super Murphy” who hits 25% grounders with lower than 45% FBs. However, to date, we have not seen a guy sustaining such high LD rates; that guy would probably have to have superhuman bat control (which probably eliminates almost all >25% K rate guys). But with modern training methods, who knows what might happen.

Looking for Evidence of a Change to the Ball

We saw an unprecedented jump in home runs in the last few years. What made it so strange was that most of it happened after the 2015 All-Star break. There is an increased awareness of launch angle and bat path, and 2015 was the first year there was a public in-game feedback, but still you would expect such an adjustment to take longer, especially since in-season swing changes are really hard to do — maybe with a whole offseason to work on it, it might have been slightly more believable.

There have been multi-factor explanations like a great rookie class of power hitters in the second half of 2015, changed approach, and other stuff like a slightly smaller zone, but really you would not expect such a multi-factor cause to happen that quickly and distinctly between two season halves. That made most sabermetric writers, including most of the FanGraphs staff, believe in a single-factor cause, most likely the ball.

There is some evidence for a changed ball, and there is also anecdotal evidence of minor-league players called up claiming the MLB ball flies farther. However, MLB so far has rejected that, and supported that with the credible name of professor Alan Nathan, albeit without really publishing the data, which further increased the suspicion.

We also did see an increase in launch angle: In 2015 in the first half, the LA of the league was 9.6, and in the second half it was 10.3, which further slightly increased in the first half of 2016 (10.4) and 2017 (10.8). The biggest jump, however, occurred between the season halves of 2015. So were the players really able to increase their LA with a single focus cue without really having much time to work on swing mechanics by just aiming higher after getting the first-half feedback? Those are the most talented athletes in the world, but still that sounds incredible.

But of course just increased elevation doesn’t explain the surge. The number of balls hit between 20 and 35 degrees (usual HR range) increased from roughly 8200 in the first half of 2015 to roughly 8600 in the first half of 2016, but the number of HRs increased from 2521 to 3082. Since less than half of the FBs between 20 and 35 go out of the park (I don’t have the exact number but I estimate 30% from the numbers I have), the 600 more batted balls in that range don’t explain 500 more HRs. That means, apart from more FBs, those also got out more, and the league saw a jump in HR/FB rate (9.5% in 2014 and 12.8 in 2016).

To research that, I looked into some Statcast stats. All stats here are just first halves of the respective seasons, because the first half of 2015 was the last “normal” HR half. Also I want to lessen weather effects.

This table shows that balls between 20 and 35 degrees do indeed fly farther and also go faster off the bat.
Average distance (20-35 LA)

2015 326 89.9
2016 331 91.6
2017 332 91.3

So does this jump in HR/FB prove a juiced ball? Not necessarily. To explain this, we have to get into swing mechanics. The attack angle is the vector of the bat’s sweetspot just before contact. Generally you can hit higher LAs (launch angles) by just hitting the bottom of the ball, but while some backspin is good, too much of it will slow down the ball. Generally the more LA and attack angle match, the higher the exit velo. That means players that try to swing up more might shift their highest velos to higher LAs. So while players couldn’t really change their swings that fast, just the intent of higher LA might have unconsciously caused a higher attack angle and thus more “flush hit” fly balls.

Evidence for the ball not being a factor is that average league EV is actually down a tiny bit. However, if the attack-angle theory is true, you would also expect that the EV of balls between 0 and 10 degrees would lower a little bit, and that hasn’t really happened.

Avg EV EV (0-10 LA)
2015 87.1 93.3
2016 87.8 93.3
2017 86.9 93.1

Another theory came from Tom Tango. He assumed that harder swinging and increased attack angles lead to higher peak EVs but also more weak mis-hits.

We do indeed see a big increase of balls hit above 105 MPH, but on the other side (and there have to be weaker hits to explain that overall EV is not up) there is an effect of more weak-hit balls in 2017, but not so in 2016.

EV >85 Balls 105
2015 96.2 19210 2960
2016 96.9 19075 3917
2017 96.7 20436 3635

To see if there is an aerodynamic effect — one theory of the juiced ball is reduced air drag due to lower seams — I looked at the average distance of balls hit at 20-25 degree LA in different velocity buckets.

EV Range 95-100 100-105 105-110
2015 366 391 415
2016 362 387 408
2017 363 391 411

You can’t really see an effect here. Balls hit at the same EV (which is measured right after exit so that air drag hasn’t done its work yet) don’t fly farther in 2016 or 2017 than they did in the first half of 2015. That means there likely isn’t really an effect of aerodynamics, at least not a big one.

So the reason for increased HRs seems to be mostly that fly balls fly faster and farther for whatever reason. We don’t see an across-the-board increase of EV, however, but simple explanations like a shift of max EVs to other launch angles don’t seem to really work either, as LAs from 0-10 (and also lower than minus 5 for that matter) haven’t really changed in their EV.

It remains mysterious what did actually happen. We do know LAs have increased some, but that doesn’t explain the whole story. But I couldn’t find real evidence for a changed ball in Statcast either. Could a super fast on-the-fly adjustment of the league between season halves based on the Statcast date really be the driving factor here?

Intellectually I really want to believe the juiced-ball theory, as it is the most elegant explanation for such a quick turnaround, but maybe it isn’t that easy.