Although the starters generally kept the Sox in the game, the bull pen didn't do a very good job closing the door. Now two of their more effective relievers, Octavio Dotel and D.J. Carrasco, are gone.
Matt Thornton is the one sure thing in the bull pen. He has been one of the best setup men in the league the last two years, posting an ERA below three both seasons while striking out well more than a hitter per inning.
Although he didn't perform to his usual standards last year, I still consider Bobby Jenks a solid reliever.
After that, things get more sketchy. Scott Linebrink was quite bad in the second half, and Tony Pena didn't exactly endear himself to Sox fans after he arrived. New addition J.J. Putz was elite a few years ago, but he has struggled with injuries the last few years.
One thing working in the team's favor is that middle relief is wildly inconsistent. Maybe the Sox will get lucky with a career year from one or two of the their relievers—much like they did in 2005. Theoretically, the pen should also have to pitch fewer innings with improved rotation depth.
That said, the Sox can't afford to throw away games in the later innings again.