Hader was optioned to minor-league camp Monday.
Hader appeared in three games for the Brewers this spring, and despite allowing eight batters to reach base across his 4.2 innings, he gave up just one earned run over that span. His season will begin with Triple-A Colorado Springs, but as the Brewers' top starting pitching prospect, he's a good bet to make his big-league debut at some point in 2017.