Kelley first managed the Minneapolis Millers for one season (). At the close of the season, he purchased the Millers and became their manager. He led the Millers through 1931, but never won a pennant; his highest finish was second, to the Indianapolis Indians, in 1928. After a sixth-place finish in '31, he retired to the club presidency, operating the Millers until he sold them to the New York Giants in . His over-all record in his 30 years as a minor league was 2,390 wins and 2,102 losses for a .532 winning percentage.