Jake Peavy has had almost two different seasons. In one season, as a member of the Boston Red Sox, Peavy struggled to keep runs off the board and the ball in the park. In the other, Peavy was an integral cog to the patchwork rotation of the San Francisco Giants. Peavy, with far more favorable conditions, flourished and helped the Giants reach the postseason. In about half the innings, Peavy accrued double the fWAR with the Giants. His strikeout rate decreased, but his walk rate decreased much more, and he stopped giving up home runs.
Since Peavy is not an overpowering pitcher, he's got to make due with guile. He has to out-think the opposition, which is a constant game of adjustments, to use an oft-cited phrase. One adjustment a pitcher can make is with his release point. After Peavy's May 18 start, in which he gave up five runs in six innings to the Detroit Tigers, his ERA/FIP/xFIP sat at 4.33/5.21/4.57. Peavy was a far below average pitcher who was having difficulty keeping guys off the bases and within the park. That's supposedly when an adjustment was made—Peavy changed his release point to a lower arm angle.
The top line graph is the per game average horizontal release point. The bottom line graph is the per game average vertical release point. After looking at these release point data acquired from Baseball Savant, it's difficult to see the change using the average horizontal and vertical release points. It almost looks as though the change did take while he was in Boston, but after he went to San Francisco, he raised his arm angle. There is some evidence that the Giants' coaches worked on his mechanics with him, and Peavy said he felt like he was "behind the ball" more with the Giants, whereas he was "around the ball" with the Red Sox.
Perhaps some visual aids will help. Below is a series of three pictures approximating Peavy's release point. The first is from April 9, the second from May 29 and the third from September 22. You can see the slight differences between each release point, camera angle notwithstanding. Notice the extra spine tilt in the third picture to get the extra height on the release point.
There are other ways to look at release point data, and data in general, one of which is the standard deviation. Below is a graph showing Peavy's horizontal release point standard deviation on a game-by-game basis. There is a stark drop on May 24th after Peavy supposedly made the change to his release point; after the change, Peavy maintained better consistency with his release point.
From May 24 through his last start with Boston on July 22, Peavy's ERA/FIP/xFIP was 5.01/4.49/4.07. Peavy's BABIP increased and his LOB% decreased, but his FIP showed better underlying performance. Peavy's strikeout rate stayed about the same, but his walk rate decreased from 11.5% to 6.3%. Unfortunately, Peavy was still prone to the long ball, but it appeared that better release point consistency was helping him overall.
This brings me to Game 2 of the World Series. Peavy started off a bit rocky, but the Royals' hacktastic ways helped him out in the middle innings. Then, in the sixth inning, Peavy seemingly lost control. After giving up a hard-hit single to Lorenzo Cain, Peavy walked Eric Hosmer. That was it; he got the hook. Here's the plot of the pitches Peavy threw to Hosmer.
Notice that although Peavy stayed low and away, two of his misses were bad misses. If you look at the plot, you'll notice that pitch No. 2 is missing. That's because it's hanging out on the Y-axis near the 3.0 vertical location notch. So, Peavy's first inning, second inning and sixth inning were really his worst innings. Below, there is a graph of the horizontal release point of each pitch through the game.
Peavy hovers around -1.5 for the middle innings, but pitches near the beginning of the game and sixth inning showed different release points. Notice especially the craziness from pitch 58, which is the valley there, onward to the end. Peavy seemed to lose his release point*, and he paid for it. Keeping a consistent release point through a game and a season is a constant battle, and Peavy lost this one.
Peavy got the hook for several reasons. One, he just got hit hard and couldn't find the zone. Two, the times-through-the-order penalty was in effect. Furthermore, Peavy's release point inconsistency, while perhaps not on Bruce Bochy's mind when he took Peavy out, could have been a contributing factor to it all.
*It is possible that Peavy shifted on the rubber, but the variation shouldn't be so inconsistent near the end if he did so.
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Kevin Ruprecht is an Editor of Beyond the Box Score. He also writes at Royals Review. You can follow him on Twitter at @KevinRuprecht.