Joel Hanrahan

By Gary Dzen/Boston.com Staff

What to expect: The Red Sox acquired All-Star reliever Joel Hanrahan from the Pirates for righthanded reliever Mark Melancon and three minor leaguers. Sox manager John Farrell has already named Hanrahan his closer. Even if he doesn't stick there, he gives the bullpen depth and provides some competition for Andrew Bailey, who was supposed to be the team’s closer last season before being injured.

Who he replaces:Alfredo Aceves was thrust into Boston’s closer role last season and had a rocky go of it. Aceves struggled with the pressure early and finished the season with a 2-10 record, 25 saves, and a 5.36 ERA.