Hoover was called up by Milwaukee prior to Saturday's game against the Cubs, Adam McCalvy of MLB.com reports.
In a corresponding move, the club optioned Brandon Woodruff and designated Tyler Webb for assignment. Hoover will likely serve as depth out of the bullpen after failing to crack the Opening Day roster. He logged a 3.92 ERA over 41.1 innings of relief in 52 games with Arizona in 2017.