The Giants optioned Whisenhunt to Triple-A Sacramento on Friday.
Whisenhunt gave up two runs in 5.2 innings during his spot start against Colorado on Thursday, but he'll now return to the minors in order to make room for Keaton Winn's (elbow) return from the injured list. Whisenhunt now owns a 3.38 ERA and 1.41 WHIP through 10.2 frames in the majors this season, and he could be an option to return to San Francisco later in the year if the big club's rotation depth is tested.