Hilliard was optioned to Triple-A Albuquerque on Thursday, Danielle Allentuck of The Denver Gazette reports.
Hilliard hit just .161 with two homers, 13 runs, 12 RBI and two stolen bases over 41 games to begin the season, and he recently lost out on playing time. The 28-year-old should have more consistent at-bats while attempting to right the ship in the minors, and he'll likely be one of the top candidates for a call-up if the Rockies need additional outfield depth.