2018 May Isolated Slugging Surgers

This year, the Baseball Savant pages at MLB.com have shared even more data, as new metrics are being calculated and published for our analytic pleasure. The Expected Statistics page calculates a hitter’s expected batting average, slugging percentage, and wOBA. Sweet! Though I can’t recall any exhaustive research studies on the predictive power of their expected metrics, I know the Statcast guys are top notch and trust they have done a good job.

That said, there are some obvious factors being ignored in these metrics. Off the top of my head, I can think of failing to account for a batter’s speed, his home park, and the effects of defensive shifting. That means these aren’t perfect metrics, but it does provide an excellent starting point for further analysis.

I’ll begin by using the xAVG and xSLG metrics to calculate an xISO and determining the difference between that mark and the hitter’s actual ISO. I don’t care about SLG itself since it’s affected by batting average. If a guy goes 100 for 100, with all those hits being singles, his SLG is going to be 1.000, which makes him look like the best power hitter in the history of the game. But his ISO would be 0.000, which is a more accurate reflection of his lack of power.

ISO Surgers
Player ISO xISO Diff
Brandon Belt 0.204 0.357 -0.153
Randal Grichuk 0.121 0.271 -0.150
Matt Olson 0.138 0.284 -0.146
Teoscar Hernandez 0.290 0.429 -0.139
Leonys Martin 0.214 0.338 -0.124
Matt Carpenter 0.137 0.259 -0.122
Joey Votto 0.140 0.262 -0.122
Anthony Rendon 0.176 0.298 -0.122

Remember how I just mentioned that park factors are ignored here? Yeah, Brandon Belt is a perfect example. He plays in one of the most pitcher friendly parks in baseball (perhaps the most pitcher friendly), so his power is annually hampered by AT&T Park. His career home ISO sits at .182, while his away mark stands at .204. It’s not as big a difference as I expected, but remember that hitters generally perform better at home. This year, he has actually posted a higher ISO at home. While he has always been an extreme flyballer, he has taken that tendency to greater heights this year, having posted his first FB% above 50%. That will boost his homer total, though it makes his .337 BABIP a bit riskier to count on.

You might quibble with my decision to include Randal Grichuk here given my lists are always only those who are “fantasy relevant”. And with Teoscar Hernandez performing so well (who xISO suggests may actually deserve even better, as crazy as that is), when Grichuk does eventually return from injury, he might not have a starting job. But man has he been one of the unluckiest hitters in baseball. His batted ball profile is all out of whack, which makes it pretty clear how messed up he was at the plate. But he obviously deserved much better. And his walk rate has surged to a career high, so there has been some good so far. I was definitely interested in buying low here, but his playing time situation is too murky for me to make that recommendation.

I wasn’t a Matt Olson fan heading into the season, but I never expected his HR/FB rate to dip to just 11.1% and ISO to a paltry .139. Because he was such a surprise last year, he’s the type of guy that his owners might be second guessing themselves for buying into last year’s half season breakout. That means he could come quite cheaply. The problem, however, is that I don’t see much upside outside of home runs. He can’t hit lefties, strikes out a lot and won’t contribute in batting average, and obviously doesn’t steal bases. I’d buy in an AL-Only league, sure, but a shallower mixed format? Don’t bother.

Geez, a .429 xISO for Teoscar Hernandez?! That’s second highest in baseball behind Mookie Betts (woah). While Hernandez showed solid power in the minors, it was never elite and never projected to reach that level. While I probably wouldn’t rush out to sell high as an owner, do acknowledge the batting average downside — it’ll be difficult to maintain that reasonable strikeout rate while posting a 15.6% SwStk%. His strategy so far has been to swing, swing, and swing some more. The more swings, the more chances one of those swings makes contact and puts the ball in play, avoiding the strikeout. It has worked for some (Adam Jones), but it’s risky.

I would have never guessed that Leonys Martin’s .214 ISO was actually well below what his exit velocity/launch angle combos suggest it should be. He has also cut down on his SwStk% and K%, and upped his walk rate to a career high. While he’s doing everything else well, he does have just one steal, but I think you just care that he’s earning positive fantasy value for a change.

Matt Carpenter is too good to continue mired in this slump for much longer. He still owns a sub-.200 BABIP, while his HR/FB rate is down for a third straight season. You have to wonder how much of this slow start is health related, but poor health should hurt his exit velocities. If we already know what those EVs are, whether he’s healthy or not shouldn’t then change his xISO expectation. I’m buying in deeper leagues and he shouldn’t cost much.

After an uncharacteristically slow start, Joey Votto has picked it up recently. But, his season line is still far below the standards he has set. All his underlying metrics look normal, so there’s little reason not to expect vintage Votto the rest of the way. Oh, and his line drive rate sits at an absurd 36.1%.

It still surprises me that Anthony Rendon’s career high HR/FB rate is just 12.3%, and just once has he posted an ISO above .186. He’s done little for fantasy owners so far this season and has attempted just one steal in which he was caught. Since he has essentially stopped stealing bases, he’s not much different than Carpenter. That’s still a solid fantasy player, but it probably isn’t as valuable as the perception. Still, if his owner is antsy and bored by his current production, by all means buy.

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Mike Podhorzer is the 2015 Fantasy Sports Writers Association Baseball Writer of the Year. He produces player projections using his own forecasting system and is the author of the eBook Projecting X 2.0: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. His projections helped him win the inaugural 2013 Tout Wars mixed draft league. Follow Mike on Twitter @MikePodhorzer and contact him via email.

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I thought one of the writers here at FG had done some correlation studies on xwOBA and found it to be somewhat predictive. I’ve been watching it closely the last couple years because it makes all sorts of sense ot me. There definitely is a speed bias to xwOBA – the guys who outperform are fast and the guys who underperform are slow. Just as one example, Miguel Cabrera has underperformed his xwOBA by 30 to 70 points every single year and is back at it this year at -.022.

I also think park effects are in play too and help explain why Castellanos consistently underperforms. While he’s no burner, he’s not slow by any means. Actually, all the Tigers do poorly in this metric so Comerica hurts them.

Ryan DC
Ryan DC

Someone did a post concluding (I think?) that balls hit to center field in Comerica are way less likely to go out than you’d expect just based on EV, LA, weather, etc, possibly due to some kind of wind effect unique to the ballpark.