Some of the other PITCHf/x analysts out there are looking at the hitting aspects or other things that can be divined from the data, but I’m still quite fascinated by the ability to classify a pitcher’s pitches. I know that’s not the be-all-end-all of baseball or of PITCHf/x, but I’m learning so much about the game from pursuing this angle, I may camp in this corner for a while.

I decided to take a look at one of my favorite players–who happens to have had quite a resurgence in the second part of this year–Royals’ former and once-again wunderkind Zack Greinke.

I split the data into three parts. The first part was his first seven starts this year, in which he compiled a 5.71 ERA on the strength of 49 hits, 11 walks, and 19 strikeouts in 34 2/3 innings. This performance resulted in his banishment to the bullpen in hopes of salvaging something from 2007 for Greinke. We only have one start recorded in PITCHf/x from this period. In this start, his fastball was recorded at 87-93 mph. Other than noting that fact, I’ve chosen to ignore the rest of the data from this start.

The second part was his relief performance, which lasted from May 10 to August 20, and for which he have 295 pitches recorded by PITCHf/x. In 38 relief appearances, he compiled a 3.54 ERA on the strength of 43 hits, 15 walks, and 55 strikeouts in 53 1/3 innings. In the data we have, his fastball as a reliever ran in the 92-98 mph range. Here’s the speed versus spin direction chart:

Greinke Speed vs. Spin Direction

As a reliever, he threw 67% fastballs, 24% sliders, 5% changeups, and 4% curveballs. The fastball and changeup groupings are pretty obvious. I used the spin rate parameter to help me separate the sliders and curveballs. I won’t reproduce that graph for his relief outings, but suffice it to say that the curveballs are the pitches with slower speed, higher spin rate, and lower spin direction.

What’s interesting to me is comparing the reliever graph to the same graph for his return to the starting rotation, which began on August 24. We have PITCHf/x data for four of his five starts since then, missing only his September 15 start at Cleveland. In all five starts, he’s compiled a 1.71 ERA on the strength of 21 hits, 8 walks, and 15 strikeouts in 21 innings.

Greinke Speed vs. Spin Direction as a Starter

His fastball still has a lot of pop in the 91-97 mph range. It will be interesting to see if he can keep that life on his fastball as he stretches out beyond 4 or 5 innings at a time. He’s also using his changeup a bit more: 75% fastballs, 15% sliders, 8% changeups, and 3% curveballs.

Here’s the spin rate vs. spin direction graph for his starter outings. I’ve labeled the x axis to show how the spin direction corresponds to break to a right-handed hitter. A pitch that broke straight down would have a spin direction of 0 degrees, break away from a righty corresponds to 90 degrees spin direction, break up (or a “rising” fastball) corresponds to 180 degrees, and break in on a righty’s hands corresponds to 270 degrees. So the spin direction tells us which way the pitch will break, and the spin rate tells us how much the pitch will break.

Greinke Spin Rate vs. Spin Direction as a Starter

Here’s the vertical break vs. horizontal break displayed in inches.

Greinke Vertical vs. Horizontal Break as a Starter

I’m excited to see Zack Greinke back on top of his game, and I hope he can stay there for years to come.

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