Welcome to the first post in my new weekly series, the GPS Location Report. This will post every week on Tuesdays and will be two parts. The first part will focus on one or two pitchers using the methodologies that I outlined in my Stuff ERA introduction last week. The ERA-Estimator is built with location entirely in mind. Each pitch has an inherent expected value for Swing, Whiff, and wOBA and I will be looking deeper into how pitchers are locating with this idea in mind.

The second part will be a weekly update to the Stuff-ERA leaderboard. I will list the 100 best pitchers based on the metric. These posts will focus solely on the Stuff-ERA values but in the future, I will be adding a tool that will help you to look at the individual components of the metric.


Dylan Bundy


The first pitcher that I wanted to look at is Angels’ Right-Hander Dylan Bundy. The former top prospect has been a breakout candidate every season since his first full-ish season back in 2016. However, due to a combination of factors, Bundy has never been able to deliver on his insane promise. So far in his career, he has posted a 4.58 ERA while showing flashes of brilliance. Yet, in his first three starts with the Angels, he has been masterful with a 2.08 ERA across 21 innings.

As many others have pointed out, Bundy seems to have made a significant change to his pitch mix. The below chart from Baseball Savant shows the decrease in fastball usage thus far.




The sharp decline in Fastball usage has been offset by an increase in Sliders mostly, with other small jumps to the Changeup and Curveball. Unsurprisingly, this has been huge for Bundy. Plain and simple his fastball get crushed. He has the 11th highest xwOBA on his fastball last season among all pitchers who threw at least 1,000 of the pitch. On the flip side, his xwOBA on the slider was the 20th best among pitchers who threw 500 sliders in 2019. It does not take a rocket scientist to see that it makes more sense for him to throw more sliders.

However, I think the more interesting trend with Bundy is less about the fact that he is throwing the slider/curve more often but is more about when he is using the pitches.



The above chart is Bundy’s breaking ball locations placed on top of the expected whiff charts that are one of the bases of my Stuff-ERA model. With Bundy switching to throwing more breaking balls, I expected to see his expected whiff rates jump. However, he is at around 12% which is in line with each of his previous four seasons. In the above chart, the black dots are the whiffs and the other dots are either balls in play or are taken.

As you can see, he is throwing a ton of breaking balls in 0-0 counts, the top-left graph. Actually, Bundy has thrown the second most breaking balls in baseball in 0-0 counts and only two of them have been put into play. Actually, among pitchers who have faced at least 50 hitters, he has the sixth-lowest swing rate in 0-0 counts. This seems to be a big key to his success right now. He is getting ahead of hitters with a large number of offspeed pitches. One of the cool aspects of my model is that I have expected swing rates for every pitch. Among the same sample of pitchers with at least 50 batters faced, Bundy’s xSwing rate in 0-0 counts is 25th best. While still very much above average, I would expect his swing rate to climb a bit.

The improvement in contact management due to the increased number of breaking balls if definitely here to stay, however, so even as swings increase and hitters catch on to what he is doing, the should continue to be a much-improved pitcher compared to the first four seasons of his career. He is the fifth-best pitcher by Stuff-ERA as you’ll see in the next section. While I think the improvements are real, he is likely not a Cy Young contender. However, Bundy should continue to be a valuable fantasy asset for those who believed in the prospect pedigree.


Stuff ERA Leaders

All stats are updated as of Sunday, August 9th. 


Stuff-ERA Leaders
Min 150 Pitches
Pitcher Stuff-ERA
Shane Bieber 2.4342
Aaron Nola 3.1009
Max Scherzer 3.1122
Corbin Burnes 3.1222
Dylan Bundy 3.1918
Zac Gallen 3.2663
Jacob deGrom 3.2799
Touki Toussaint 3.2927
Luis Castillo 3.3129
Tyler Chatwood 3.3803
Yu Darvish 3.4002
Carlos Carrasco 3.4207
Frankie Montas 3.4522
Jalen Beeks 3.4636
Dinelson Lamet 3.4862
Jonathan Hernandez 3.4891
Blake Snell 3.5350
Jesus Luzardo 3.5364
Chris Stratton 3.5512
Zack Godley 3.5537
Kyle Wright 3.5546
Brandon Bielak 3.5552
Nate Pearson 3.5693
Kevin Gausman 3.6031
Trevor Bauer 3.6313
Asher Wojciechowski 3.6410
Tommy Milone 3.6552
Tyler Mahle 3.6622
Walker Buehler 3.7046
Tyler Glasnow 3.7218
Josh James 3.7276
Zach Plesac 3.7322
Lucas Giolito 3.7332
Sonny Gray 3.7367
Hyun Jin Ryu 3.7554
German Marquez 3.7554
Anibal Sanchez 3.7576
Scott Barlow 3.7686
Robbie Ray 3.7739
Patrick Corbin 3.7797
Kyle Gibson 3.7978
Alex Cobb 3.8004
Clayton Kershaw 3.8031
Kyle Hendricks 3.8041
Ryan Yarbrough 3.8183
Brady Singer 3.8206
Trevor Richards 3.8219
Lance McCullers Jr. 3.8235
Aaron Civale 3.8344
Gerrit Cole 3.8378
Griffin Canning 3.8390
Trevor Williams 3.8452
Kenta Maeda 3.8492
Garrett Richards 3.8572
Joe Musgrove 3.8589
Julio Urias 3.8607
Yusei Kikuchi 3.8751
Wade LeBlanc 3.8923
Lance Lynn 3.8966
Tejay Antone 3.9089
Zach Davies 3.9122
Jose Berrios 3.9139
Tyler Anderson 3.9162
Mike Soroka 3.9176
Justus Sheffield 3.9322
Andrew Heaney 3.9499
Luke Weaver 3.9589
Mike Clevinger 3.9608
Spencer Turnbull 3.9633
Adrian Houser 3.9663
Logan Webb 3.9894
Michael King 3.9934
Brandon Woodruff 3.9964
Zack Greinke 4.0159
Max Fried 4.0497
Gio Gonzalez 4.0529
Dustin May 4.0541
Drew Smyly 4.0740
Yohan Ramirez 4.0817
Zack Wheeler 4.1058
Matt Shoemaker 4.1363
Chris Bassitt 4.1428
Marco Gonzales 4.1459
Merrill Kelly 4.1506
Sean Manaea 4.1768
Antonio Senzatela 4.1922
Chris Paddack 4.1986
Charlie Morton 4.2088
Kendall Graveman 4.2089
Dallas Keuchel 4.2186
Dylan Cease 4.2235
Alec Mills 4.2252
Ivan Nova 4.2322
Kris Bubic 4.2364
Cristian Javier 4.2373
Michael Wacha 4.2571
Ryan Weber 4.2788
Randy Dobnak 4.2870
James Paxton 4.3091
Patrick Sandoval 4.3110