While working on something Erasmo Ramirez said — that his slider was always in the zone anyway, so he should probably use it to steal strikes rather than for swinging strikes — it became obvious that breaking pitches are much less effective in the zone than out when it comes to swinging strikes. Curves, in particular, are much better outside the zone. You get about one third of the whiffs on a curve in the zone as you do outside of the zone.
Separately, I’m working on a piece for The Hardball Times Annual about command. In it, a few pitchers talk about the difficulty of commanding breaking pitches. “Nobody throws anything that’s truly straight,” is how Trevor Bauer put it.
While sorting the in and out of zone whiff rates, and thinking about command, it came to me that the two are related. Maybe that’s a duh, but a big part of quantifying command is the problem of breaking balls and changeups and their movement. A breaking ball in the zone may often be a hung breaking ball, which contributes to the lower whiff rates.
Let’s take a look at the pitchers that have the most disparate results on their non fastballs inside and outside the zone first, and then try to find a way to spot these pitchers by movement.
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