Hager was optioned to Triple-A Reno on Thursday.
Hager was with the major-league club since mid-May, but he saw sporadic time in the starting lineup over the last month. The 29-year-old has hit .240 with two doubles, four runs and three RBI over 28 games in the majors this year, but he should see more consistent at-bats in the minors. Sergio Alcantara was added to Arizona's active roster to serve as a utility man.