Keller, 21, allowed one earned run on three hits in six innings Thursday for High-A Bradenton. He walked one batter while fanning four.
Keller rebounded from an ugly first start of the season in which he was bombed for five runs in just 2.1 innings. The 6-foot-3 righty had a transcendent year in 2016, posting a 2.35 ERA and 138:19 K:BB in 130.1 innings, mostly at Low-A. He has emerged as one of the top pitching prospects in baseball but may not hit the majors until 2019.