Wily Peralta’s Release Points and Sliders | Disciples of Uecker

Disciples of Uecker

We'd like to go to the Playoffs, that would be cool.

From the get-go, the Los Angeles Dodgers hit Wily Peralta yesterday. Carl Crawford started the damage by singling off of Peralta’s very first offering. The next two outs would be Peralta’s best sanctuary from the Dodgers’ offense, and the lonely first inning run simply foreshadowed things to come. One can argue that Peralta did not receive the best defensive support in his second inning, as both Rickie Weeks and Jean Segura botched plays. However, by the time Peralta walked two Dodgers home, any point about defensive support was moot. The Brewers’ top pitching prospect, and in many ways the wild card for pushing the rotation one direction or the other, had his roughest afternoon yet.


Now that we’re nearly two months into the season, we can slice Peralta’s big league performance into thirds. Alongside Peralta’s exceptional replacement outing to close the 2012 season, his April and May performances show a startling trend of strike outs, walks, and homers:

Month Year BF K BB HR IP R
Season 2012 113 23 11 0 29.0 8
April 2013 126 15 12 3 28.7 18
May 2013 118 16 7 3 23.0 26

In some regard, Peralta’s April to May walk trends show an encouraging trend, but alongside his home runs and overall performance, his walks almost suggest a pitcher working too aggressively, rather than controlling the strike zone and limiting the damage. Meanwhile, Peralta’s strike outs dropped, and his home runs increased (although, given Miller Park, his home run rate isn’t nearly as troubling as his strike out rate).

In both April and May, Peralta’s decrease in walks and strike outs turned the righty into a “contact” pitcher, where more than 75% of his batters faced knocked the ball into play.

One of the likeable traits for Peralta is that he recovered from a rough early 2012 in AAA, and he improved to the point of performing as one of the National League’s best short-term replacement pitchers. That type of improvement shows a tenacious pitcher, or one that can weather adversity and regain his approach. So, I’m certainly not throwing in the towel on Peralta, but given his disappearing strike out rate and Batted-Ball-In-Play approach, one can certainly ask, “what’s going on with Peralta?”


Since I had yesterday afternoon off, I was ready to sit back and enjoy a Brewers broadcast. Unfortunately, the early game performance made the definition of “enjoyment” rather subjective, so I investigated my question about Peralta. The righty flashed electric stuff at times in 2012, and worked effectively with basically two fastballs and a slider. What changed?

Notably, the first area of change is Peralta’s release point. In 2012, Peralta released the ball closer to the arm side of the mound, and arguably lower and further away from his own body. In 2013, Peralta’s release point is higher, and he’s either releasing the ball closer to his body, or changing his position to the first base side of the rubber. Either way, his release point is effectively higher and closer to his body in 2013.

You might ask, “what does Peralta’s release point matter?” Well, release points and arm angles (and, in some cases, even where a pitcher sets up on the rubber) can influence how a pitcher is able to spin the ball, break his pitches, and get the optimal movement and angle against the batter. Similarly, as arm angles and release points change, so too does a batter’s view of the ball. Depending on the way batters approach a pitcher, a shifting arm angle could cause that pitcher to lose deception on his motion. Similarly, if a batter can pick up the ball easier, well, that gives the batter one more moment to consider that offering.

Peralta’s slider has arguably suffered the most from his mechanical shift. Alongside his higher-and-closer release point, Peralta’s 2013 slider is neither breaking away from righties nor dropping as much as his 2012 slider. This type of shift in break and movement is significant because it changes his slider from a pitch that actively offsets his primary and secondary fastballs, to a pitch that, well, is just a slower pitch that drops from his fastball. While it’s good that Peralta is continually maintaining the velocity differential between his fastball and slider, it’s not good that the pitch isn’t breaking or dropping as much.

Alongside a shifted release point, Peralta’s less active slider takes away one of his secondary weapons. This arguably changes Peralta’s ability to use his fastball effectively, as well. Specifically, Peralta is currently locating his slider for strikes 11% less frequently than in 2012, which changes the way that he needs to use his fastball (notably, he is throwing both of his fastballs in the zone much more frequently). This especially affects Peralta’s secondary, or sinking/moving fastball, which he is throwing much more frequently in 2013: Peralta is throwing that pitch for strikes more frequently, getting more whiffs, and also getting more batted balls in play.

A less potent slider that doesn’t land in the zone as much, accompanied by a different release point with a potentially more visible ball, arguably takes away two different weapons from Peralta: (1) Peralta cannot deceive batters with the movement or location of his slider, and (2) Peralta cannot threaten batters with both his fastball and slider. Effectively, Peralta’s fastball becomes a sitting duck. If his slider doesn’t land for strikes, his fastball must hang around the zone, and if the visibility of those pitches changes in favor of the batters, the batters will have an easier time dealing with both pitches.


At the end of April, Peralta threw two consecutive quality starts. Notably, his arm angle was closer to its 2012 position than his higher 2013 point.

I am not sure what this shift in mechanics suggests. In one regard, this shows that Peralta has not completely lost his release point, and could potentially leverage his mechanics and repeat them to effectively locate, break, and move his pitches. On the other hand, this also shows the oft-fleeting nature of pitching mechanics. As upset as fans might be about Peralta’s performance, we should also appreciate just how momentary and difficult good pitching mechanics can be; although Peralta hasn’t completely lost it, he also hasn’t limited the damage when he doesn’t have his best release point. This time, the details are easy to see on the field and in the box score.

Baseball-Reference. Sports Reference, LLC. 2000-2013.
TexasLeaguers. Trip Somers, 2009-2013.

Movement and release point charts from TexasLeaguers, Trip Somers, 2009-2013.

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