Pitch sequencing, in my opinion, is the next big thing in the field of baseball research, and despite what Samsung might like to tell you, it isn’t here yet. There has been some tremendous work done, but we’re still a long ways away from aggregating findings into one clearly defined picture of how pitch sequencing exactly works.
But we might as well continue to add to the findings. I looked at one aspect of pitch sequencing – shifts in the called strike zone – last month. Next, I’m looking at how best to set up different types of pitches. We’ll start with four-seam fastballs, and, so as to keep it simple for now, focus just on the fastball and on the pitch immediately beforehand. Not pitches before that in the same at-bat, not pitches to the same batter earlier in the game, not pitches to that batter from a different game.
Intuitively, you might expect changing speeds on the batter to be an effective way to mess with their swing and timing. A changeup, then, should be a good pitch to set up a fastball – changeups are generally 10-plus mph slower than the same pitcher’s fastball. Curveballs, too, should be decent setup pitches, as should sliders to a lesser extent. (Sliders are usually thrown harder than curves.) As it turns out, though, it doesn’t quite work that way.
Contact% = Foul balls + balls in play per swing
There’s some year-to-year variation, but, by and large, changeups are ineffective ways to get swings and misses on the fastballs which follow them. Now, bear in mind, the scale here isn’t so large – it’s a few percentage points each way. But it’s still pretty clear that changeups, as well as curveballs, don’t help the pitcher throw a better fastball the next pitch.
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