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.
What little scouting information I could find on Edinson Volquez agreed with the diagnosis of four pitches: a four-seam fastball, a two-seam sinking fastball, a changeup, and a curveball.
September 12, 2007 at 12:57 am
[...] it. If you were to read one Gameday site (apart from mine!), read his. Anyway, today he has a post about Edinson Volquez, following on from my post about him on the weekend. Mike takes what I had posted and goes a little [...]
September 12, 2007 at 5:27 pm
I like the spin info, but, visually, (a) it is not as intuitive as the pfx/pfz charting, and (b) you showed how well you can convey the same information using the x/z charting.
As far as discovering two fastballs amongst (noisy) data, it is critical.
I’m going to mess around and see if spin rates are related to pitch recognition (or lack thereof). Before that I plan on looking at OOZ along with pitch type.
I certainly will use the spin analysis in identifying pitch types (and automating it).
That shouldn’t be in parentheses; the thought is that if PITCHf/x analysis (and normalization) keeps supporting, or clarifying, traditional scouting (the good bits of it), imagine the leveling of the playing field, and the economic impact of widespread implementation of PITCHf/x – the system becomes as common as lights, everywhere.
September 12, 2007 at 10:42 pm
Harry, the way to make the spin direction more intuitive is to put it on a polar plot and add some niceties to it. For presentation that would probably be worthwhile. For pitch classification purposes it’s more work and doesn’t add much. But you definitely have a point that a physical understanding or correlation to the data is critical for communicating what’s going on.
The pfx/pfz graph is great for showing what the batter sees, and probably makes the most sense for presentation of the data.
However, I find that I often can’t tell pitches apart on the pfx/pfz graphs until I see them as separate pitches on the speed/spin direction graph first.