The Pirates optioned Sisk to Triple-A Indianapolis on Tuesday.
Sisk walked six but allowed just two runs on three hits with seven strikeouts over six innings during spring training, but it wasn't enough to earn a spot on the Opening Day roster. The left-hander had a 3.57 ERA and 25:10 K:BB across 17.2 frames in the majors last year and should receive a look with the Pirates at some point this season.