The Rockies optioned Blalock to Triple-A Albuquerque on Sunday.
With Cal Quantrill (tricep) returning from the injured list to start Sunday's game against the Cubs and Antonio Senzatela (elbow) set to return from the IL to start Monday versus the Diamondbacks, the Rockies no longer had room in the rotation for Blalock. The right-hander made six starts for Colorado following his Aug. 12 call-up from Triple-A, logging a 1-3 record with a 6.07 ERA, 1.82 WHIP and 20:19 K:BB in 29.2 innings.