In early May, the Oakland A's were still trying to compete but their bullpen was making that goal difficult. In a shrewd move, they picked up the out-of-favor Edward Mujica from the Red Sox for virtually nothing. Mujica had experience, some fairly recent success, and strong K:BB credentials. He got off to a nice start, with five scoreless outings to begin his A's career, but this is 2015 so he was hit by a line drive and suffered a fractured thumb that knocked him out for a month.
Since his return, Mujica just hasn't been the same.