Davidson was recalled from Triple-A Gwinnett on Monday.
Davidson was on the big-league roster for a single day in mid-April but didn't get into a game. He made his major-league debut last season, giving up seven runs (two earned) in 1.2 innings of work. In a pair of Triple-A starts this season, he's fared far better, allowing just a single run on seven hits over 14 frames. Fellow lefty Jesse Biddle was optioned in a corresponding move. Davidson has been almost exclusively a starter in the minors, but there's no obvious spot for him in the rotation at the moment, so he'll likely be taking Biddle's bullpen job for now.