As the Yankees put together a hot May, the team’s fans have watched Alfredo Aceves blossom into a very effective and useful piece in the bullpen. While he has made just nine appearances, he has shown poise and ability that could provide the shaky Yanks’ pen with a solid piece.

On the season, Aceves has hurled 19.2 innings over those nine appearances. He has allowed 16 hits and has walked just three while striking out 18. He is 3-1 with a 2.75 ERA, and opponents are hitting .219/.256/.342 off him. While his BABIP allowed is .259, lower than the average and thus suggesting that opponents may hit him better in the future, he has limited the damage by throwing 65 percent of his pitches for strikes. It’s amazing what confidence and good stuff can do for a reliever

Over the last few weeks, we’ve explored the various roles of Alfredo Aceves. Rebecca wrote a guest post suggesting that he could be the next Ramiro Mendoza, an unheralded but valuable member of the Yankee championship teams, and the Yankees have deployed Aceves as such. Six of his nine appearances have been of the multiple inning variety. The other three were either in extra innings or in the 9th inning of what was then an 11-0 blowup.

Meanwhile, the infamous Eighth Inning debate rages on in the Yankee Universe. More important than any of the other eight innings, the eighth inning has been a thorn in the Yankees’ side since the end of Steve Karsay’s career. (Ed. Note: Hyperbole.) As the Yanks remain committed, as they should be, to keeping Joba in the rotation and as Brian Bruney and Damaso Marte work their ways back from injuries, the Yanks have struggled to build a proper bridge to Mariano. Jose Veras is a nightmare; Phil Coke hasn’t been able to get the job done. You know the story.

Today, in a very well-researched piece that relies upon some advanced bullpen metrics not often seen among the Yankee beat writers, Marc Carig proposes Alfredo Aceves for the eighth inning. Aceves, notes Carig, is second among team relievers in WXRL or expected wins added over a replacement level pitcher, and he has excelled so far in high-leverage situations. Noting that the analysis is subject to a small sample size warning, Carig concludes:

But Aceves has many of qualities typically associated with good set-up men, specifically impeccable command. And though he’s not overpowering with his fastball, Aceves can throw any pitch at any time, making him equally effective against lefties and righties.

To me, it only makes sense to reward Aceves by having him work in these high-leverage situations as much as possible. And the only way for the Yankees to do that is to scrap the idea of using him as a jack-of-all-trades reliever.

Using Aceves for multiple innings essentially wastes him in non-essential situations that can be worked by lesser relievers. What’s worse, multiple inning stints would mean at times that Aceves would have to rest as much as two days between appearances.

He’s much too valuable for that.

I certainly see Carig’s point, and he makes a very compelling case for the move. Yet, as I believe that Mariano Rivera should not be saved for a save situation that may never come and should be used in the highest leverage situations late in games, I don’t think the Yankees need to limit their use of Aceves to just the eighth inning.

What they have in Aceves is a versatile reliever who could pitch the eighth in close games and can prevent other games from getting out of hand. He can throw multiple innings on back-to-back days and can provide flexibility in a bullpen short on that very trait. There is no need to mess with that, and Joe Girardi seems to agree.

“You could think about it but I do like the flexibility he gives us,” Girardi said. “And with a couple of young starters that we have, sometimes you need a little bit of length out of your guys.”