Zimmermann allowed a run on two hits and a walk and struck out five over four relief innings in Wednesday's 9-1 loss to the Red Sox.
Zimmermann worked the final four innings of the game, with the only run against him coming on a wild pitch in the seventh inning. The 25-year-old has allowed six runs over seven innings in two appearances (one start) this year. It's unclear if he'll get another look in a long-relief role before the end of the season.