You want a Dojji type to keep an eye on, here's one of the better ones in the Sox system, AA year old Portland reliever Dustin Richardson.
Richardson was a starter last year and started out well but fell apart as the season went on. he maintained good strikeout numbers despite his struggles (114 K's in 104 IP) so clearly the stuff was still good, but Richardson was clearly not going to hack it as a starter.
So they moved him to the bullpen for this year, and so far the returns have been good. Richardson has been channeling Dan Bard from last year with his numbers, both the good (about 12 strikeouts per 9 innings) and the bad (5.8bb/9).
He's on the older side at 25, and his fastball is more deceptive than it is powerful according to the Soxprospects scouting report, but he seems to harness his stuff well and may have a future as a matchup lefty, especially if he can harness his command juuuuust a bit better. Since the Sox currently have only Oki for lefthanders in their pen, and only Jones and Lopez (and their reverse splits) in Pawtucket, that's a niche Richardson might be the one to fill down the road sometime.