Hamilton was placed on the 10-day injured list Saturday with right shoulder soreness.
Hamilton began his season with three scoreless relief appearances, but he faltered Tuesday by giving up two runs on one hit and two walks while recording just one out. His shoulder issue could provide an explanation for the rough performance, and he'll be sidelined as a result. It's unclear whether he'll have to spend more than the minimum of 10 days on the injured list. The move is retroactive to Aug. 12, and southpaw Bernardo Flores was recalled to serve as the 29th man for Saturday's doubleheader.