'Alfredo Aceves' photo (c) 2011, Keith Allison - license: http://creativecommons.org/licenses/by-sa/2.0/With the announcement that Aceves will be the Boston Red Sox closer on opening day there was a mix of emotions from Red Sox Nation. The Globe sure wasn’t pleased as this mornings articles included picking Vicente Padilla or the insane idea of moving
Daniel Bard into the role. That gem was from Nick Cafardo who obviously hasn’t paid attention to the injury history of pitchers moved from starter to reliever or vice versa with little time to prepare. Aceves value has been largely held in his flexibility to pitch multiple innings and in many situations. It looks like he’ll take that a step further taking on the full time closer role.

I’ve had questions about Aceves as a full time starter as his sample so far has exposed him a bit in that role. It’s not a huge sample with only 208 batters faced, but in that time his K/BB plummets to 1.09 where he is usually a solid 2.86 as a reliever. Having to face hitters a second and third time really hurts Aceves as his K/BB drops significantly in that situation.

That said, his ability to take 2-3 innings in the middle of the game was a huge boost to the 2011 Red Sox and would have been a nice benefit for this current squad. Unfortunately though they have to try him in a role he has faced even fewer times. Aceves has currently pitched in 25 save situations and has pitched quite well. He has a 2.02 ERA in those spots with a 2.50 K/BB.

An added bonus with Aceves versatility is he can easily be asked to pitch more than just the last three outs of any game. This actually helps the pen as Melancon could be asked to help even in the seventh inning and Aceves could come in to start the eighth or in the middle of the inning. If used this way he almost becomes closer and setup and saves an inning of work from the rest of the pen.

The big question now is can Aceves maintain what he has done? With a FIP of 4.08, a xFIP of 4.77 and a SIERA of 4.13 normally I would be dreading this move. His BABIP last season was an unquestionably low .231 and his HR/FB was only 5.3 percent. If these numbers don’t scream regression I don’t know what does. The problem is I don’t expect a huge regression.

That doesn’t mean I don’t trust the numbers, but more I know to trust some trends. In 240 innings pitched Aceves has a BABIP of .235 and a HR/FB of 7.2 percent. While 240 innings isn’t huge it’s enough to notice a potential trend. If you’re looking for data to support this look no further than some other relievers in the past few years. Troy Percival, Rafael Soriano and Mike Adams have each topped 300 innings pitched and maintained at BABIP under .246.

Does he share anything with this group that might identify him as someone who can do this for the next 200 innings? Looking at this group they are all fly ball pitchers with solid K/BB rates. Soriano and Percival largely feature only three pitches while Adams and Aceves are more rounded. Aceves throws a four seam fastball, a sinker, cutter, curve and changeup. There is some overlap in pitches, but nothing really sticks out as what they do that might be the same.

Looking specifically at Aceves his ability to throw a sinker was curious for someone with a 39 percent ground ball rate. What is even more interesting is what his sinker does. Looking at his Pitch F/x data his sinker results in a GB/BIP 37.04 percent of the time. It also results in a pop up 14 percent of the time. That might not mean much, but thankfully BrooksBaseball.net converts those to PitchIQ scores. His GB/BIP scores 80 and PU/BIP 146.*

*The simple explanation of PitchIQ is like any other weighted stat like OPS+. 100 is average for the league meaning his GB/BIP for a sinker is 20 percent below average and his pop up/BIP is extremely high for a sinker.

Only his curve has a lower than average rate of pop ups than league average. In 2011 Aceves had an infield fly ball rate of 14.7 percent. The league average in 2011 was 10.6 percent. It appears that outside of his curve Aceves is able to manufacture outs by way of weak infield fly balls. He’s not on par with the greats like Mariano Rivera who has a
career infield fly ball rate of 16.1 percent, but Aceves works his pitches up in the zone (as you can see below) and while getting fly balls they appear to be weaker hits.

Aceves Pitches against RHH


Dismissing Aceves based on his sabermetric stats would be foolish, but also expecting him to maintain these numbers would be just as dangerous. His career ERA still stands at 2.93 and his FIP is 4.03. I think it’s safe to expect him between the two and closer to the lower value than the higher. Only MARCEL and Bill James projection systems agrees with me giving him a 3.39 or 3.46 ERA respectively. The rest including STEAMER and OLIVER expect him to become the 4.00 ERA pitcher his peripherals suggest.  I’m still leaning towards the positive projections and expect Aceves to be solid in the closer role.