MLB Advanced Analytics: wOBA-xwOBA Pitching Update

Published: Aug 01, 2019

Last week we examined Weighted On-Base Average minus Expected Weighted On-Base Average (wOBA-xwOBA) for hitters. It also a great tool for pitchers now that the sample has become larger. An xwOBA higher than wOBA indicates luck on balls in play. A higher wOBA means a pitcher is having poor luck to some extent.

Here is the leaderboard of wOBA-xwOBA for a minimum of 1000 pitches.

Rk.	Player	Results	wOBA - xwOBA
1	Chris Stratton	0.368 - 0.315	0.053
2	James Paxton	0.358 - 0.308	0.05
3	CC Sabathia	0.360 - 0.318	0.042
4	Blake Snell	0.304 - 0.263	0.041
5	Dylan Bundy	0.350 - 0.313	0.037
6	Max Fried	0.325 - 0.294	0.031
7	Drew Pomeranz	0.371 - 0.340	0.031
8	Jordan Lyles	0.351 - 0.322	0.029
9	Noah Syndergaard	0.302 - 0.274	0.028
10	Freddy Peralta	0.336 - 0.310	0.026
11	Ross Stripling	0.306 - 0.281	0.025
12	Carlos Carrasco	0.353 - 0.329	0.024
13	Zach Eflin	0.339 - 0.317	0.022
14	Yusei Kikuchi	0.358 - 0.337	0.021
15	Drew Smyly	0.389 - 0.368	0.021
16	Collin McHugh	0.327 - 0.307	0.02
17	Anthony DeSclafani	0.324 - 0.304	0.02
18	Kyle Freeland	0.387 - 0.367	0.02
19	Martín Pérez	0.313 - 0.294	0.019
20	J.A. Happ	0.344 - 0.325	0.019

James Paxton could be getting bad luck due to playing home games in Yankee Stadium. It should impact a LHP less, but it’s still a hitters park.
Dylan Bundy tends to be too hittable at times. His bad starts are probably skewing things.
Could Yusei Kikuchi be settling in as an effective off-speed pitcher? He’s getting good results for his underlying metrics.
Drew Smyly is with a new team and has a new lease on the 2019 season. It’s interesting that luck has been on his side so far.

Here are the pitchers getting a bit more luck than the batted balls against them indicate.

Rk.	Player	Results	wOBA - xwOBA
1	Brett Anderson	0.309 - 0.349	-0.04
2	Mike Fiers	0.289 - 0.325	-0.036
3	Andrew Cashner	0.312 - 0.348	-0.036
4	Zach Plesac	0.308 - 0.341	-0.033
5	Merrill Kelly	0.319 - 0.350	-0.031
6	Ryan Yarbrough	0.265 - 0.296	-0.031
7	Chris Paddack	0.251 - 0.280	-0.029
8	Shane Bieber	0.274 - 0.303	-0.029
9	Yonny Chirinos	0.288 - 0.316	-0.028
10	Luke Weaver	0.283 - 0.307	-0.024
11	Hyun-Jin Ryu	0.248 - 0.272	-0.024
12	Brad Keller	0.313 - 0.337	-0.024
13	Félix Peña	0.304 - 0.328	-0.024
14	Julio Teheran	0.301 - 0.322	-0.021
15	Mike Soroka	0.266 - 0.287	-0.021
16	Jeff Samardzija	0.299 - 0.317	-0.018
17	Patrick Corbin	0.279 - 0.297	-0.018
18	Zack Greinke	0.261 - 0.279	-0.018
19	Michael Pineda	0.310 - 0.327	-0.017
20	Jake Odorizzi	0.296 - 0.313	-0.017

Some names on here don’t have the best fastball. Fiers and Cashner particularly. They’ve lost velocity from their career peaks and are getting by with what’s left of their arm.
We saw Mike Soroka on this list earlier in the season. It indicates that he creates weak contact via pitching control.
Merrill Kelly is another pitch to contact type. He hasn’t been very effective. It’s a hard time to pitch that way with the juiced ball.
High-velocity pitchers like Pineda have shown up here before. A straight fastball could be part of what’s at play.

As always, I encourage you to examine the wOBA-xwOBA results for yourself and adjust parameters as you see fit. It’s great to isolate individual pitch types, too. Fantasy trade deadlines aren’t far away and most teams could use more pitching. This is a great angle for taking advantage of your competition.