Black was optioned to Triple-A Sacramento on Monday, Shayna Rubin of the San Francisco Chronicle reports.
Black will head down to the minors after making his second start of the season Saturday against the Reds. He fared well, allowing one run on four hits and two walks while striking out two over 4.1 frames. The Giants have enough off days to go with a four-man rotation until Blake Snell (adductor) returns next week. Nick Avila was recalled in a corresponding move.