The Giants outrighted Santos to Triple-A Sacramento on Monday.
The transaction will free up on a spot on the 40-man roster for right-hander Eric Cerantola, whom the Giants claimed off waivers from the Royals. Santos owns a 6.89 ERA and 1.84 WHIP with an 11:11 K:BB across 15.2 innings at the Triple-A level this season.