I think the only improvements are going to come from reinstating guys from the DL. Crazy season so far. All infielders are healthy but nearly all outfielders are injured. Same with the rotation and bullpen. One bullpen injury and the rotation has been decimated.
They have leveraged an ok season from a good bullpen and good defense. Might as well continue to play to those strengths by cutting guys who aren't hitting and suck on defense and replace them with guys who can catch the ball.