The bullpen currently includes two proven righty setup men in Brad Ziegler and Junichi Tazawa, in addition to the emerging Matt Barnes. Those three relievers are probably going to stick with the club under any circumstances.
There are also two veteran starters who were recently moved to the 'pen in Joe Kelly and Clay Buchholz. Kelly still has Minor League options, but the Red Sox might be leery of sending him back down so soon after he was called up.
Buchholz is in the final season of his contract, and could possibly be moved to a club in need of a starter.