Pitch Type Killers

In a continued effort to not overreact to the first month of games, I’m circling back to an idea I meant to investigate over the offseason, which is hitters who crush certain pitch types. I have a pair of theories related to this research. The first and most obvious one is that hitters who have success against certain pitch types should perform better against pitchers who either rely more heavily on or are most successful when using that same pitch type. The second is that hitters who are more balanced in their performances against various pitch types should be better hitters long term because it prevents pitchers from discovering a hitter’s weakness against a pitch type and throwing more of that type of pitch to him.

There is a lot to do to fully answer those questions, so for this article, I wanted to start simple with leaderboards of batters who have performed well against various pitch types since the start of the 2015 season. I decided to structure those leaderboards by taking the difference between batter wOBAs in plate appearances ending in a specific pitch type and batter wOBAs in plate appearances ending with any pitch type. So whereas Bryce Harper might rightly be called a curveball killer because he has a .323 wOBA against curveballs and the average wOBA of all hitters is .313 since the start of 2015, I am not going to call Harper a curveball killer because he performs worse against curveballs than he does against other pitch types. Meanwhile, I added a few more restrictions to the leaderboards. To qualify, hitters must have 300 total plate appearances since the start of 2015 and at least 50 plate appearances against the leaderboard’s specific pitch type.

Let’s start with fastballs.

Fastball Killers (wOBA Diff), 2015-16

Batter	All	Fastballs	Diff
Pedro Alvarez	.330	.443	.113
Francisco Lindor	.362	.470	.108
Jorge Soler	.313	.415	.102
Kendrys Morales	.365	.454	.089
Leonys Martin	.266	.351	.085
Khris Davis	.340	.421	.081
Russell Martin	.328	.405	.077
Preston Tucker	.326	.402	.076
Adam LaRoche	.286	.362	.076
Jayson Werth	.304	.379	.075
Mike Trout	.412	.485	.073
Yan Gomes	.285	.356	.071

For me, Francisco Lindor is the most interesting name because I’m intrigued by the idea that pitchers might learn something from hitters’ early-career successes and failures and then change their approaches in facing those hitters. And while Lindor has crushed fastballs, he has a below-average .270 wOBA against changeups and .303 wOBA against sliders. This early in the season, the pitchers a batter has faced could have as much to do with the pitches he has seen as the general strategy the league would want to take, but it is interesting to note that his percentages of fastballs seen has increased from 57.5 percent last year to 64.2 percent this year. He’s also continued to perform well offensively this season.

Curveball Killers (wOBA Diff), 2015-16

Batter	All	Curveballs	Diff
Kris Bryant	.370	.451	.081
A.J. Pierzynski	.326	.398	.072
Wilson Ramos	.277	.336	.059
Gregory Polanco	.315	.373	.058
Brandon Phillips	.324	.374	.050
Andrew McCutchen	.381	.428	.047
Ian Desmond	.288	.331	.043
Marlon Byrd	.320	.352	.032
Starling Marte	.347	.377	.030
Todd Frazier	.339	.362	.023
Howie Kendrick	.322	.345	.023
Kevin Kiermaier	.311	.334	.023

Kris Bryant really stands out on this list, both because of his youth and potential and because his .081 wOBA difference on curveballs compared to all pitches is more than double that of the No. 8 hitter on this leaderboard. In contrast to Lindor and his fastballs seen, Bryant has seen a precipitous drop in his curveballs seen this season, from 7.4 percent of his pitches last season to 0.9 percent this season.

Changeup Killers (wOBA Diff), 2015-16

Batter	All	Changeups	Diff
Dee Gordon	.337	.504	.167
Mike Napoli	.328	.481	.153
Carlos Gomez	.310	.441	.131
Brandon Guyer	.350	.473	.123
Josh Donaldson	.405	.527	.122
Starlin Castro	.299	.409	.110
Alejandro De Aza	.325	.429	.104
Justin Smoak	.334	.428	.094
Asdrubal Cabrera	.324	.414	.090
Ian Kinsler	.343	.432	.089
Rougned Odor	.333	.420	.087
Chris Coghlan	.333	.414	.081

Josh Donalson’s .527 wOBA against changups and Dee Gordon’s .504 wOBA against changeups are two of the three highest wOBAs by batters against any pitch types. As a point of reference, Bryce Harper has a .470 wOBA against all pitches, so Gordon morphs into a better Bryce Harper when he sees changeups. Neither Donaldson nor Gordon has seen much change in their percentage of seen changeups this year. And as for Harper, he leads all hitters in wOBA versus both fastballs and sliders and is 26th against changeups. So, you know, good luck with that MLB pitchers.

Slider Killers (wOBA Diff), 2015-16

Batter	All	Sliders	Diff
Steven Souza	.322	.439	.117
Didi Gregorius	.302	.402	.100
Mookie Betts	.347	.427	.080
Aaron Hill	.273	.331	.058
Albert Pujols	.328	.379	.051
Mike Zunino	.238	.289	.051
Luis Valbuena	.321	.368	.047
Adam Eaton	.350	.395	.045
Charlie Blackmon	.345	.388	.043
Troy Tulowitzki	.328	.365	.037
Daniel Murphy	.345	.375	.030
Eduardo Escobar	.324	.348	.024

The trio of Souza, Gregorius, and Betts are well clear of the field in slider wOBA differential, and the latter two have seen massive drops in their percentages of sliders seen so far in 2016. For Gregorius, that drop is from 14.4 percent to 2.9 percent. For Betts, it’s 17.8 percent to 9.3 percent. Meanwhile, Souza’s percentage of sliders is slightly up from 17.7 percent to 20.7 percent.