The x-z component of the spin rate is a very useful tool for classifying Perez’s pitches. His cutters have a low spin rate in the x-z plane, and his change-ups can then be separated from his fastballs based on speed (as well as spin parameters). I have 41% fastballs, 39% cutters, 17% changeups, and 1% curves.

Perez’s curveball is pretty slurvy. I’m comfortable calling it curveball based on the speed and his personal identification, but its spin characteristics are somewhere between slider and curve.

I am unsure about the pitch with Sportvision ID of 080330_213157. It has some characteristics of both a cutter and a changeup. If I had to choose, I’d say it was a cutter.

Before seeing this I had analyzed Odalis’ pitches from the pitch f/x data as 44% fb, 38% ct, 12% ch, 1% sl. But if Perez says he throws a curveball, the “slider” must be a curveball, even if it is a pathetic one. The pfx_x value did appear to be too positive, so once that’s fixed gameday will probably call more cutters (or at least call more sliders). There’s not much of a difference between Odalis’ fastball and changeup, so it’s hard to draw the line between the two. All-in-all he’s a hard pitcher to analyze. The division between the cutter and fastball is not clear either.