The Orioles optioned Zimmermann to Triple-A Norfolk on Sunday.
Zimmermann was sent out to make room on the 26-man active roster for first baseman Ryan Mountcastle (vertigo), who was reinstated from the 10-day injured list in a corresponding move. During his brief stay with the big club, Zimmermann made a lone appearance out of the bullpen, giving up an unearned run in one inning of relief in Tuesday's game against the Yankees.