The Difference Pitching on the Edge Makes

Note: I found some errors in the data. Data below has been corrected, as well as some conclusions — BP

Yesterday, Jeff Zimmerman examined how Tim Lincecum‘s performance has depended to some extent on his ability to pitch to the edges of the plate. Last year, Lincecum was one of the worst starters in the game in terms of the percentage of his pitches thrown to the black. Coincidently (or not so coincidently), Lincecum suffered through his worst season as a professional.

As with many things, Jeff and I happened to be investigating this issue of the edge simultaneously. Of course, we were not the first to dabble in this area. Back in 2009, Dave Allen noted that differences in pitch location–specifically horizontal location–led to differences in BABIP.

Like Dave, I was curious about the overall impact that throwing to the edges–or the black–has on overall performance. My thinking about pitchers throwing to the edges naturally led to some hypotheses:

  1. Throwing a higher percentage of pitches on the edges leads to lower FIP.
  2. Throwing a higher percentage of pitches on the edges leads to lower ERA.
  3. Throwing a higher percentage of pitches on the edges leads to lower BABIP.
  4. Throwing a higher percentage of pitches on the edges is associated with lower four-seam fastball velocity.

I think the first three hypotheses are intuitive, but the last one stems from the idea that as a pitcher ages and loses zip on their fastball they cannot remain successful unless they increase their avoidance of the heart of the strike zone.

Jeff and I are still tinkering with the methodology. For this article, I decided to classify the edge as the area three inches (essentially, about the width of a baseball) to the left or the right of each side of the strike zone. I also adjusted the zone for right and left-handed batters per Mike Fast’s work (see here):

Edge for right-handed batters:

px <=-.765 AND px >=-1.265 & px >=.75 AND px <=1.25

Edge for left-handed batters:

px <=-.85 AND px >=-1.35 & px >=.845 AND px <=1.345

For frame of reference, I calculated the Edge% (i.e. the percent of all pitches thrown that qualify as being on either edge) for all qualified pitchers since 2007 and broke them out into percentiles:

Percentile Edge%
90th 21.0%
75th 19.7%
50th 18.6%
25th 17.3%

When we look at the average performance of pitchers in each percentile and compare them to each other, a few interesting patterns emerge*:

And here are some basic correlations:

First, our initial hypothesis that the more a pitchers throws to the edges the higher their strikeouts and lower their walks is confirmed. The correlation between Edge% and K% is only .08, and Edge% and BB% is -.11. Interestingly, the difference in average K% between the top decile and bottom quarter of edge throwers is almost 0%. However, the difference jumps to about 1% between the top and bottom quartiles; same for BB%

This pattern holds pretty well across a number of metrics, including BABIP (>=75th Percentile minus <25th Percentile -.005, -.11 correlation with Edge%), ERA (-9, -.18), and FIP (-.17, -.21).

Pitchers that work the edges more also see higher swings outside the zone, along with less contact.

There is also a slight difference in the rate at which pitchers throw to the edges and their velocity. Pitchers that worked the edges the most threw their four-seam fastball about 1 mph slower than those with the worst Edge%, and relied on that pitch less (39.7% vs. 54.6%). Pitchers that threw more cutters, sinkers, and two-seamers lived on the edges at a higher rate.

So that’s the high-level, how does this actually look for specific pitchers?

Taking a quick glance at the data I found two pitchers that nicely illustrate how changes in their Edge% correspond to their overall improvement: Doug Fister and David Price.

Fister came up with Seattle in 2009 and posted decent, but not outstanding, numbers (96 ERA-, 120 FIP-). That year, Fister flirted with top quartile performance in terms of Edge% (19%). The following year, however, Fister’s Edge% dropped below the 50th percentile (18.2%), and with it his ERA- jumped to 106 and his K% and SwgStr% tumbled (12.9% and 4.4%, respectively). Fister did manage to post an above-average FIP, but this was mostly due to cutting his HR/FB by over half in 2010.

In 2011, Fister broke out. His Edge% jumped into elite range (21%) and he posted ERA- and FIP- that were also in elite company (73 and 78, respectively). Additionally, Fister’s K% jumped to 16.7%, and would further jump to 20.4% the following year:

Year Edge% ERA- FIP- K% SwgStr%
2009 19.0% 96 120 14.1% 6.9%
2010 18.2% 106 93 12.9% 4.4%
2011 21.0% 73 78 16.7% 6.7%
2012 21.5% 83 81 20.4% 8.0%

We see a similar story for David Price. After a brief call-up with the Rays in 2008, Price entered the rotation in 2009 and posted a slightly below average ERA- and FIP-. In 2010, Price elevated his already good Edge% to elite status (21.2%) and saw his ERA- and FIP- plummet. Price has since maintained that elite Edge%–even improving it to a league-leading 22.5% in 2012–and along with it he had arguably his best season in 2012 (66 ERA-, 77 FIP-, 24.5% K%).

Year Edge% ERA- FIP- K% SwgStr%
2009 19.4% 104 109 18.3% 7.5%
2010 21.2% 69 86 21.8% 9.8%
2011 21.4% 90 86 23.8% 8.4%
2012 22.5% 66 77 24.5% 8.3%

None of this is to say that Edge% is the explanation for pitcher performance. The correlations exist, but they are relatively small. However, the preliminary results show a pretty good relationship between pitchers adjusting their approach and learning to control the edges of the zone better and a corresponding change in their overall performance.

Jeff and I are continuing to work on this topic. For example, we think it makes sense to take Edge% and look at it in the context of counts. Are pitchers more successful throwing fastballs in fastball counts because they largely throw those fastballs on the edges? Does throwing to the edges account for why some pitchers have a higher percentage of strikeouts due to called strike threes?

Needless to say, there are a number of places one can go with this, and we’ll be exploring a number of them in the coming weeks.


*Because of the changes made to how PITCHf/x classifies pitches, the data for pitch-type classifications only uses 2010-2012 data.

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Bill works as a consultant by day. In his free time, he writes for The Hardball Times, speaks about baseball research and analytics, consults for a Major League Baseball team, and has appeared on MLB Network's Clubhouse Confidential as well as several MLB-produced documentaries. Along with Jeff Zimmerman, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Tumblr or Twitter @BillPetti.

39 Responses to “The Difference Pitching on the Edge Makes”

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  1. Woodman says:

    Great article. Can we expect to see a “Edge%” stat on Fangraphs in the future?

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  2. Matt Hunter says:

    Awesome awesome stuff. The next step would be to figure out if Edge% correlates year to year, yes? Great work, Bill (and Jeff).

    Also, minor typo in the 4th point: “Throwing a higher percentage of pitches on the edges leads is associated with lower fastball velocity.”

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  3. Chicago Mark says:

    Good stuff Bill. I know there’s a lot more stuff/data to put together on this. But I hope this moves to pitch sequence location. Not certain how to explain. But changing location high/low and in/out is said to make a big difference also. Also, I’ve heard talk about pitchers that can’t/won’t pitch to certain quadrants of the plate. Some pitchers just can’t pitch inside for whatever reason. It would be interesting to find out the performance of these pitchers compared to those who use all 4 quadrants.

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  4. MrKnowNothing says:

    I would’ve thought that pitching on the edge would correlate with lower velocity because guys would be taking a tick or two off in exchange for greater control.

    Is there a way to determine if pitches around the edge are, on average, slower? (Or maybe that’s in this data and I’m terrible at reading it.)

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    • Patrick says:

      I can not agree at all. When pitching in college my best control often correlated with my best stuff. Proper mechanics pitch to pitch lead to higher velocity and better control. Any time I was trying to be careful or take something off for better control it led to a change in release point and poor location.

      Reading books by Randy Johnson, Tom House, etc. They would suggest the exact same results–so I am not attributing this only to one mediocre college career.

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      • Adam says:

        But there’s a difference between “blowing it out” and staying within yourself, maintaining your tempo and trying to work downhill.

        While on ‘average’ the differences between the ‘average’ pitcher in each percentile seems marginal, that’s the ‘average’. If Mr. Petti had used more examples, the differences in edge% and velocity, and general levels of success (I suspect) would be more highlighted. Perhaps I’m wrong.

        This is pretty great stuff. I think the things that pitchf/X developments are allowing the baseball industry to do are remarkable. I like pitch f/X…it’s where metricians and “throwback” types alike can be looking at ‘advanced’ data, yet know that it still fits in easy-applicable and ‘imaginable’ game situations (for those aforementioned ‘throwback types’).

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    • Dave S says:

      Or maybe the real life results are selecting the data, and not vice versa.

      ie. pitchers that can’t blow you away with stuff NEED to live on the edges… or they get pounded, and get run out of the league… leaving you with these sorts of data.

      because they’re whats left.

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  5. Jon says:

    Great article, I would love to see this subject explored more. One thought about the unexpected correlation between fastball velocity and edge% is that maybe you should fix on a particular ERA (or FIP or xFIP or something). Your hypothesis that pitchers who have bigger fastballs would be less able / have less need to hit the corners makes more sense if you look at pitchers with about the same level of overall effectiveness. It’s possible that the pitchers who have more overall talent both throw harder and have a higher edge%, but if you look at a fixed level of overall talent then the two become negatively correlated as you’d expect.

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    • Bip says:

      One assumption is a pitcher needs at least one of good velocity and good command to stay in the big leagues. A pitcher with bad FB velocity and bad command as represented by Edge% would be out of the league. So what’s left are the guys who have one or the other or both. This would create a negative correlation.

      But if there is a stronger negative correlation between vFB and Edge% among pitchers with similar “effectiveness” as you suggest, that would be quite interesting indeed…

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  6. Scott says:

    I see Fister at 16.8% EDGE on the 2012 link….sorting problem?

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  7. Absolutely wonderful.

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  8. MakeitRayn says:

    This is nice, but what about breaking it down even further? Edge percentage inside vs away?

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  9. Lee Panas says:

    Fantastic work. Since strikeouts and avg seem to be better in the 75+ percentile than the 90+ percentile, perhaps there is such a thing as pitching too much on the edge for certain types of pitchers. The interesting thing will be looking at more pitchers progression over time as you did with Price and Fister.

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    • Bip says:

      It’s possible that once you get into the 90th percentile you get to the guys who, knowing they don’t have the stuff to blow guys away, have focused on command to an extreme degree. So having below average stuff makes a guy more likely to improve his command, meaning that command and stuff, as represented by K%, are not independent.

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  10. tigerdog says:

    This is excellent work! I particularly like the Price- Fister references.

    Fister is an interesting pitcher to study. You would think that such a tall right hander would be relatively easier to run on, yet he has allowed a grand total of ten stolen bases in his career, now over three seasons. He’s actually very quick to the plate with a slide step delivery, and he obviously is able to generate a lot of downward plane on the ball with a 6 foot- 8 inch frame.

    He has quietly posted a 3.33 FIP from 2010- 2012, which is sixth lowest in the AL- also 9th in ERA and 8th in WAR. With all that going for him, if he’s able to paint the corners as well, he’ll be scary good.

    What we’re really measuring here with the Edge% is command. The count could often dictate location, such as in the case of a pitcher throwing one off the plate on an 0- 2 count, or coming down the middle on a 2- 0 count. But overall, you’d think that a pitcher that is in the higher range of Edge% is demonstrating better command.

    Nice work, guys.

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  11. Macek says:

    Hey, this is great. Are the samples large enough to look within season for an individual pitcher? It seems possible that a higher edge% is driven by better mechanics which leads to better “stuff” making it not causal but just associated. Maybe comparing pitches on the edge vs. off the edge during the same time period could help to get at the causality a little bit more. Also it is completely possible that you have done that or are planning to do that and I haven’t read the article well enough to notice.

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    • Macek says:

      I just realized that I was confusing. I meant on the edge vs. in the middle of the plate. Off the edge makes it sound like I was talking about balls and not strikes.

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  12. chuckb says:

    This is fascinating stuff. I really appreciate it. You mentioned that the correlations were small but when you add a little to the K rate, subtract a little from the BB rate, and subtract a little from BABIP, the 3 combine to have a pretty large impact on a pitcher’s success. A pitcher can go from an average pitcher to a good pitcher just by doing those little things. My point is that even though the correlations are small, they add up to be something much larger.

    Really great. Now I need some time to just sit around and look through all the data. Thanks.

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    • Baltar says:

      No, sorry, you can’t do that.

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    • Bip says:

      King Felix is a good example. His K%, BB% and GB% are all good but not great. However, being above average in all three makes him an elite pitcher. Pitchers more commonly excel at two and lag in a third.

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  13. Glenn DuPaul says:

    Obviously there’s a lot more work that can be done with this, and I agree with everyone else that this is fantastic stuff. You’re going to be restricted some what by sample, but I would love to see how well Edge% correlates with K% or ERA in the subsequent season.

    It’s great to explain maybe why David Price’s BABIP was so low in 2012, but it’d be even more valuable to see what this metric tells us about future performance. I figure both of you have thought of this/plan on doing it, but if it adds significant predictive value, that would be awesome.

    Keep it up, fellas

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  14. SirCub says:

    Holy cow do I love this. Making observations, setting forth a hypothesis, developing a metric to test it, then testing it! It’s so… scientific! Great work, as always.

    So, if this stat correllates fairly well with BABIP, do you think it could be used as part of an explanation for pitchers with hit suppression? And if so, do you foresee a way to use Edge% to determine a pitchers ‘true BABIP’?

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  15. Steve Staude. says:

    This is outstanding. I wish I’d had this when I was doing some of my expected BABIP articles in FanGraphs Community Research (article 1 and article 2). I think I’ll have to see how well I can integrate this into my research.

    Will you look into the vertical equivalent of this?

    I think it would also be interesting to see the relationships between Edge%, Heart%, and Outside% vs. BABIP (and other factors, like SwgStr%) when broken down by pitch type.

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    • Bip says:

      The vertical case seems a little more difficult. It seems that the effectiveness of pitching up vs down in the zone depends more on the pitcher, including his delivery, release point and the types of pitches he throws. Different pitches from the same pitcher probably have different effectiveness high vs low. The horizontal edges are are probably more reliably good for the pitcher when contrasted with the middle of the zone.

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      • Steve Staude. says:

        Good point, but that’s why I’d also be interested in the pitch type breakdown when it comes to the vertical equivalent of this.

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  16. Sean says:

    Great article. Just one small nitpick, but in the table “> 25” percentile should be “< 25" percentile. Can't wait to see where this goes.

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  17. chanelclemente says:

    It would be interesting to see what pitch selection correlated with a successful ‘edge pitcher’. For instance, here, in the Bay Area, it’s something of a truism that Lincecum’s decline seems to have paralleled his inability to get his 2 seam FB in the edge zone.

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  18. jdbolick says:

    Very cool. Any guesses as to whether or not Edge% is consistent enough for individuals to be predictive or if it’s a tool best served to autopsy prior performance?

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  19. No offense intended, and I am not a traditionalist who is anti sabermetrics, but isn’t this getting just a little silly? You seem to have gone through several hoops and formulae to explain to us that it’s a better idea to try and not groove pitches down the heart of the plate.Uh,no kidding.This is not stop the presses news.Some baseball people learned that a while back.

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    • Bip says:

      There are usually good reasons to do a statistical test that confirms common knowledge. Here are some, in this instance:

      -With statistics, instead of getting a qualitative answer (e.g. yes it is good to pitch to the edges) we get a quantitative answer. We see exactly what percentage of ERA variation is explained by a pitcher’s ability to pitch to the zone, as well as the magnitude of the effect.
      -We can measure which pitchers actually do it and how well. Instead of having general knowledge, we have specific knowledge about each pitcher
      -We can see if Edge% is a skill that is repeatable or possibly a randomly varying result that explains some randomness in ERA
      -There is a chance that we may actually debunk common knowledge, so it’s worth checking even if we don’t stand to learn anything if it’s confirmed

      There are probably more.

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  20. Bip says:

    Maybe you can combine this with the the earlier article of strikezone by count and actually physically adjust what is considered the “edge” to reflect what the effective edge is in that count. Certainly pitchers don’t calculate precisely what an umpire is likely to call, but I’m also certain they know that a hitter’s count leads to a larger strike zone and a pitcher’s counts lead to a small strike zone. Therefore a pitcher who is good at pitching to the edges would purposely use a bigger zone and compensate for a smaller one.

    Am I correct in thinking that Edge percentage is as a percentage of all pitches thrown? Maybe you could try the analysis again but as a percentage of all pitches in the zone. When a good pitcher throws a pitch out of the zone, it’s often the case that he meant to do it. As it is, doing this is penalizing good pitchers, since bad pitchers will throw more balls, but they also get into fewer favorable counts and then have to throw more pitches in the zone to compensate. Many good pitchers have low Zone%, so it seems to me that if we’re assuming a pitcher throws to the edge on purpose, it should also be assumed he meant to throw it in the zone, and pitches intended to be out of the zone are noise.

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