I'm with those who see this move as primarily affecting Tim Wakefield* -- although more in terms of likely-needed insurance. It is also part of a pattern (along with bringing in Miller, re-signing Hill and Oki, and signing Reyes) where they are comitting to Doubront as a SP.
It's not clear that Aceves is a better SP than the healthy Tim Wakefield we saw through age 42. He is almost certainly better that the healthy Wakefield we saw last year, or what Wakefield is projected for this year. Wakes be given the opportunity to bounce back at age 44, which is by no means impossible for a knuckleball pitcher but nothing you'd want to bet on.
Aceves should be at Pawtucket, waiting for a SP injury, at which point Wakefield gets a rotation spot and Aceves, rather than Doubront, gets the call-up for the long relief job. That emphasizes how much they want to give Doubront a full development year rather than have him spend a significant chunk of it as an underworked pen member. That in turn maximizes Doubront's trade value as a SP for next winter -- and also keeps open the possibility of Dice-K pitching well enough to establish some trade value with one year left on his contract, with Doubront then serving as (at the very least) a bridge to Ranaudo.
By mid-season, of course, Aceves could well have Wakefield's job. Should Wakefield bounce back, however, Aceves will be at the head of the group of guys (including Coello, Bowden, Miller, Hill and/or Reyes, and Albers and/or Atchison if they clear waivers) trying to wrest the last set-up job from whoever wins it in ST.
There seem to be a lot of candidates for the last three spots in the pen, in terms of who we'll see down the stretch--the 11 guys already mentioned plus Tazawa.
*At the MLB level. Adam Mills now needs an injury to someone ahead of him to keep his PawSox rotation spot, and Kris Johnson probably needs two.
Edited by Eric Van, 09 February 2011 - 02:59 PM.