After Sonny Gray turned in another abysmal start on Wednesday, allowing seven runs over only 2.2 innings, manager Aaron Boone insinuated that a move to the bullpen could be in Gray’s future. Well, the future is now. Sonny Gray has been moved to the bullpen, and recently acquired Lance Lynn will take his spot in the rotation.
Moving a struggling starter to the bullpen is nothing new. In fact, it’s become the de-facto fix in recent years. Not too long ago Chad Green was a fledgling starter in the Yankees’ system. However, a move to the bullpen allowed him to stick to his fastball and slider (his two best pitches by a wide margin). Combine that with the velocity increase that comes with pitching in shorter intervals, and Chad Green turned into one of the best relievers in baseball in 2017.
Pitchers generally are at a disadvantage when facing a lineup multiple times in one game, and Sonny Gray is no exception. He posted a 6.23 ERA when facing an order more than once. The main counterpoint to this is that Gray has been plenty bad the first time through the order as well (4.70 ERA), so would moving to the bullpen really help?
Moving to the bullpen affords a pitcher a change in approach. Relievers generally stick to their two best pitches, which for Gray are his sinker and curveball. Josh already touched on how being a two pitch pitcher could benefit Gray. All I’ll add to what he already said is that opposing hitters have a wOBA of .341 and .255 against Gray’s sinker and curveball respectively, as opposed to .453 and .612 against his 4 seam and changeup.
Another change that comes from pitching in the bullpen is an uptick in velocity. Starting pitchers will often pace themselves because they are expected to be able to throw ~100 pitches. Relievers, on the other hand, don’t hold back because they are only expected to throw one inning at a time.
A little extra velocity might be just what Sonny Gray needs to regain his effectiveness. We’ve already established that Gray’s sinker is the more effective of his two fastballs. There seems to be a small correlation between Gray’s sinker velocity and his start quality in 2018. In the nine starts Gray’s average sinker velocity was under 93 mph, his ERA is 7.64. In starts where it was above 93 mph, his ERA dips to 4.34. That would make him a respectable fifth starter, and would be much better than the 5.56 ERA he is currently sporting.
The trend continues when Gray’s sinker velocity climbs above 94 mph, albeit with a very small sample size. In the two starts his sinker’s average mph was above 94, he has thrown 14 shutout innings.
A move to the bullpen means that Sonny Gray can focus on his two best pitches, his sinker and curveball. It stands to reason that as a reliever Gray could be a valuable piece for the Yankees headed down the stretch if he can throw those pitches more effectively, and with more velocity.