Tommy Kahnle’s Changeup Change
Earlier this week, Miguel Castro’s hard changeup caught my eye. It’s a weird, good pitch, and it’s thrown by a pitcher who might otherwise fade into the background. What’s more, he’s still bad against lefties despite a spectacular pitch for attacking them. About the only thing that made sense to me in the whole scenario was that Castro uses his changeup to attack lefties, the way right-handed pitchers are supposed to.
We’ll get to whether that’s true in a moment. First, let me introduce you to a righty pitcher who looks at this conventional wisdom — changeups to lefties, sliders to righties — and says eh, pass. Maybe not introduce you, actually, because he’s a notable pitcher on a marquee team, but at least alert you to his weirdness. Meet Tommy Kahnle, the man who throws his changeup when he shouldn’t.
As a rule, pitchers hate changeups to same-handed batters. Of all the pitches that righties threw to righties in 2019, only 7.1% were changeups or splitters (a splitter behaves almost exactly like a changeup, and pitch classification algorithms sometimes struggle to differentiate between the two, so for the remainder of this article I’ll be lumping both pitches together). On the other hand, they love them against lefties — 17.5% of right-to-left pitches were changeups. It’s pitching 101.
Kahnle surely took pitching 101; he just doesn’t seem to care. His changeup is his best offering, and he absolutely leans on it against lefties. 59.6% of his pitches to lefty batters in 2019 were changeups. It can’t even properly be called a secondary pitch; it’s just a primary pitch! Nothing to see there — a changeup-heavy pitcher throws a lot of changeups to opposite-handed batters. Where it gets interesting is when he faces righties. What does he do there, in the matchup his pitch wasn’t designed for? Why, he throws a changeup 44.2% of the time, of course.
He’s not alone in this weirdness — Héctor Neris and Tyler Clippard, just to name two, do similar things. But Kahnle interests me, because he wasn’t always this way. In 2017, he was spectacular. A 2.59 ERA, a 1.84 FIP, a Gerrit-Cole-facing-minor-leaguers 37.5% strikeout rate and a minuscule 6.6% walk rate — he was nothing short of dominant. That year, he threw a changeup to righties 14.7% of the time. Huh? Read the rest of this entry »