The Brewers optioned Drohan to Triple-A Nashville on Sunday, Curt Hogg of the Milwaukee Journal Sentinel reports.
The left-hander was in the mix for a rotation spot but will instead begin the season in the minors after posting a 4.26 ERA, 1.26 WHIP and 15:4 K:BB over 12.2 innings during spring training. Drohan, who was acquired from the Red Sox in the Caleb Durbin trade in February, is still likely to make his Brewers debut at some point this season.