Mitch Keller’s First Two Seasons
What happened to Mitch Keller in 2019 and 2020 will probably never happen again to a non-position player who throws more than 20 innings. In 2019, Keller had a .475 batting average on balls in play. Not only is that the highest in Pittsburgh Pirates’ history, but the highest of all time, in at least 40 innings of work.
The thing is, it wasn’t like Keller was giving up line drives 40% of the time or was ranked as one of the worst pitchers that year in terms of exit velocity or hard-hit rate. Keller had a 28.7% line drive rate and was in the 83rd/61st percentiles of exit velocity and hard-hit rate, respectively. That line drive rate might not be great, but when nearly half of the batted balls put in play against you fall for hits, something is going wrong that is out of your control.
Chances are, he wasn’t going to do that again. There have only been 19 times when a guy threw 40+ innings and had a .400+ BAbip, and Keller was the first ever to have a .450+ BAbip. Although Keller didn’t have a super high BAbip, he would, however, go on to have a super low BAbip.
In 2020, Keller pitched 21.2 innings and had a .108 BAbip. A 7.7% line drive rate mostly fueled this, but it’s not as if Keller had an 80% ground ball rate. His ground ball rate was still around average at 44.2% (the average was 42.7%). He was also well below average in terms of exit velo and hard-hit rate, ranking in the 47th and 23rd percentile, respectively.
It was just the 24th time ever a guy had 20+ IP and a BAbip under .150. Heck, it was the first time a guy had a sub-.110 BAbip. Although the chances of something like this happening again isn’t zero, it’s pretty darn close. The only way it might happen again is if a non-two-way player position player pitches 20+ innings.