Yusmeiro Petit and Chase Anderson Disagree
For the last 15 years, Yusmeiro Petit has cast a spell over opposing hitters. He’s never thrown hard — his highest average fastball velocity was 89.6 mph in 2017, more than a decade into his career. He’s never been an All-Star, never received award votes. He’s been sketchy at times — his rookie season for the Florida (!) Marlins produced a 9.57 ERA. He didn’t pitch in the majors in 2010 or 2011. Through it all, however, he’s kept going, showed up and provided competent innings. He’s almost 36, and it feels like he might pitch until he’s 80.
That consistency is merely an illusion, however. When Petit first made the majors, he was pretty bad against lefties. Most righties get a little bit worse against left-handed batters; they strike out roughly two percentage points fewer opponents and walk roughly two percentage points more. Petit, on the other hand, turned into a pumpkin:
Split | TBF | K% | BB% | wOBA | FIP | xFIP |
---|---|---|---|---|---|---|
vs. L | 1210 | 17.4% | 8.6% | .342 | 5.02 | 4.67 |
vs. R | 1412 | 25.2% | 4.0% | .293 | 3.46 | 3.62 |
That split is through the end of 2017. I’m now going to do something that I strongly urge you not to do in your investigations of platoon splits — chop them up into smaller pieces. Since the beginning of the 2018 season, Petit’s platoon splits look different:
Split | TBF | K% | BB% | wOBA | FIP | xFIP |
---|---|---|---|---|---|---|
vs. L | 315 | 20.3% | 5.1% | .257 | 4.26 | 4.39 |
vs. R | 417 | 22.5% | 3.6% | .260 | 3.42 | 4.34 |
It’s a small sample, but I’m inclined to believe it. From 2008 (the beginning of pitch tracking data) to 2017, Petit threw his changeup to lefties 22.1% of the time. Since the beginning of 2018, he’s more or less doubled it, to 41.3%. Changeups are a righty’s best friend against lefties, so the improvement makes sense. Read the rest of this entry »