Manager Craig Counsell described Ashby's injury as more of a fatigue issue following Thursday's loss to the Mets, Will Sammon of The Athletic reports.
Ashby was diagnosed with left forearm tightness after exiting Thursday's matchup in the bottom of the fifth inning, but Counsell said the southpaw's early examinations didn't reveal anything too concerning. The 24-year-old will be evaluated further Friday, but he's optimistic that he'll be able to make his next scheduled start. If he's deemed healthy enough to pitch, Ashby tentatively lines up to take the mound at home against the Cardinals on Tuesday.