The Rockies optioned Sullivan to Triple-A Albuquerque on Sunday.
Colorado summoned Sullivan from Triple-A on Saturday to make a spot start in place of Tomoyuki Sugano, who was unable to recover from his back spasms as quickly as anticipated and was placed on the injured list. Sullivan dropped to 0-3 in Saturday's 6-4 loss to the Giants, serving up six earned runs on 12 hits and two walks over 5.2 innings. He'll now head back to Triple-A and give up his spot on the active roster to right-hander TJ Shook, who was recalled from Albuquerque to provide the Rockies with extra coverage in the bullpen heading into Sunday's series finale.