Swap in the bullpen The Oakland A’s made a change in their bullpen Saturday morning. The team announced that they called up reliever Austin Pruitt from Triple-A. To make room for him on both the 40-man roster and the active 26-man roster, fellow reliever Justin Grimm was designated for assignment. The A’s signed both pitchers over the offseason as minor league free agents. Grimm was named to the Opening Day roster and pitched in 15 games, posting decent overall stats but struggling in pressure situations. His strikeout and walk numbers were lackluster but he was among the best in the…