McMahon is out of Wednesday's lineup against the Giants, Thomas Harding of MLB.com reports.
Despite hitting safely in all four games (5-for-17) since being recalled, he will take a seat with southpaw Derek Holland on the mound for the Giants. He appears to be occupying the strong side of a second base platoon while DJ LeMahieu (thumb) is on the disabled list. The righty-hitting Daniel Castro will start at the keystone and hit seventh.