McGuire was optioned to Triple-A Salt Lake on Monday.
McGuire and Oliver Drake were cast off the active roster in order to make room for Albert Pujols (knee) and Jaime Barria. Across seven appearances with the Angels this year, McGuire has logged a 5.94 ERA and 1.56 WHIP over 16.2 innings. He will likely return to the rotation at the Triple-A level in order to keep him available as an option if Los Angeles requires a spot starter in the future.