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Alfredo Aceves just missed out on the starting rotation coming out of Spring Training only to be named the Boston Red Sox new closer in the wake of the injury to Andrew Bailey. Whether he’s starting or closing games, Ace brings a strong arsenal of pitches and great intensity to the mound. He was a major part of our pitching staff last season and at this point, it seems he will have an even greater role this season.
After seeing Aceves in a large percentage of his 114 innings with the Red Sox, I feel like I know his work. Before writing my player profile of Ace, I had a pretty good idea about his stuff and what I could expect from him. That is until I noticed this-

For just a second, ignore the small number of dots on the right side.* Aceves has a wide range of release points, spanning around a 2.5-3 foot range horizontally, an extreme variation. He also varies the height of his arm between a 1 and 1.5 feet., just bit more While it is not unheard of for pitcher’s to change up their arm angle, a more normal level of variation but still a bit high. These wide variations struck me as worthy of further investigation.
*Ok, second over- WTF, is up with those? Did Ace try throwing a few pitches lefty? Did he experiment with some kind of super surprising behind the back delivery? I must know! Alright, back to serious issues, people-
For reference, take a look at Josh Beckett’s release point groupings. His grouping is far more typical of a right-hander in the Major Leagues.
Both the vertical and horizontal range is closer to 1 foot in range. Consistently repeating your delivery is extremely important for most pitchers and, with his long track record of success, it is no wonder that Beckett does it so well. So, is the wide variation in Aceves release point a reason for concern, or is he using varied deliveries to fool hitters?
The first thing I noticed watching video of Aceves seemed to solve the mystery of the wide horizontal range. Against lefties, Aceves pitches from the right side of the rubber (from the catcher’s view) and against righties he moves across to the left side. Looking at his release points against lefties confirms this.
*Again, with the dots on the right!
There is still some wider than normal horizontal variation, but the grouping begins to look more like one would expect. Most of that seemingly radical variation is just a side effect of Ace stepping up in a different place, right?
Doh! Against righties, we still get a wide range of release points, which is even stranger than just varying his arm angle at random. Aceves may vary his positioning against righties, which would be an extremely strange. He typically sets up at the left edge of the rubber, but sometimes, like in the Opening Day loss to the Tigers, he appears to set up in the middle of the rubber.
Look at this appearance from September 19, 2011- Aceves is clearly at the far edge of the rubber against righties. His long side three-quarters motion leaves his release points all in the same area, at the far edge of the range for his release points.
Now look at this outing from June 8, 2011, where he appears to be in the middle of the rubber.
Here, his release points are tightly grouped, a foot to the right from his start later in the season.
Should we be concerned about this? Maybe. Alfredo Aceves has been less effective, against righties than lefties in his career. His FIP is 4.30 against lefties and 4.76 against righties. As a righty with a strong cutter and two-seamer, we would expect Aceves to be able to have some platoon advantage. Instead, he has reverse splits. Is this a result of his inconsistent positioning?
Most pitchers set up in one place to simplify things and to give themselves a consistent place to throw from. Reposition to adjust to hitter handedness makes some sense, as it could help to make certain pitches more effective. However, it is hard to understand what the logic would be behind Aceves various positions against righties. The ubiquitous use of video in Major League clubhouse, it’s hard to believe that this I something that has gone unnoticed by staff and trainers. Still, I don’t know what the purpose could be.
As the Red Sox come to depend more and more on Ace, this minor quirk could be come important. If this inconsistency is hampering his ability against righties, it will need to be addressed. Conversely, if Aceves is actually gaining some advantage from this, the Red Sox staff will need to help him exploit it to greater effect.