Santillan was promoted to Low-A Dayton earlier last week and was named to the Pioneer League All-Star Game, though he won't participate in that, Better Off Red reports.
Santillan had a 3.92 ERA, 1.23 WHIP and a 46:16 K:BB over 39 innings at Billings in the Pioneer League. The 2015 second-round pick is still pretty raw, but at least he has shown that he can miss bats.