I’ve been impressed for a while by the analysis that Steve West does of the Rangers’ pitchers using PITCHf/x data. His recent article about Edinson Volquez made me eager to try out my new spin rate toy on Volquez’s fastballs.
Sure enough, the speed versus spin direction graph clearly shows the difference between the “rising” four-seam fastball and the “sinking” two-seam fastball. It’s a difference that’s visible in the horizontal and vertical break graphs, too, and Steve comments that there may be two separate fastballs hiding in the data, but using spin direction we can see them plain as day.
The four-seamer runs 91-96 mph with mostly backspin and a little sidespin, corresponding to a spin direction of 200-220 degrees. The two-seamer runs 90-95 mph with a larger component of sidespin, corresponding to a spin direction of 220-245 degrees.
This graph also shows the changeup sitting at 80-85 mph with the spin direction varying between mostly backspin (210 degrees) to all sidespin (270 degrees). I left the curveball off this graph so that we could see the difference between the fastballs a little better, but the curve runs 77-82 mph with mostly topspin and some sidespin, corresponding to a spin direction of 35-80 degrees.
The spin rate graph confirms the diagnosis of the four-seam and two-seam fastballs, showing that the two-seamer has slightly slower spin.
Again, I left the curveball off the graph, but its spin rate ranges from 600-1600 rpm, similar to the changeup.
Finally, I want to take a look at the vertical and horizontal break on the pitches and show that our four pitch groupings do show up on that graph, too.
The four-seamer has a vertical break of +8 to +13 inches and a horizontal break of -3 to -7 inches. The two-seamer has a vertical break of +5 to +9 inches and a horizontal break of -7 to -11 inches, consistent with the “sinking” nature of the two-seam fastball.
The changeup has a vertical break of 0 to +5 inches and a horizontal break of -3 to -8 inches, and the curveball has a vertical break of -2 to -7 inches and a horizontal break of +3 to +7 inches.