Blach was optioned to Triple-A Albuquerque on Wednesday.
Blach was promoted by Colorado on Tuesday and will return to the minors after surrendering four runs over 1.1 innings against the Padres. The left-hander has appeared in 19 games this season and has a 6.46 ERA, 1.49 WHIP and 21:11 K:BB across 39 frames.