The Rockies promoted Flexen from Triple-A Albuquerque on Friday ahead of his start against the Athletics on Saturday, Suzie Hunter of TheDNVR.com reports.
Flexen holds a 7.71 ERA and 1.86 WHIP across 42 innings this season, but he will join a Rockies rotation that is desperate for healthy arms. Saturday will mark Flexen's fifth start of the season -- the first four came with Seattle -- and while his stats haven't been great and he will be pitching at Coors Field, he will have the benefit of facing the worst offense in the majors.