Santillan got a major-league spring training start Thursday against the Brewers, allowing a run over 1.2 innings.
Santillan had a big year at two levels last year, first posting a 2.70 ERA at High-A Daytona before moving on to Double-A Pensacola, where he had a more pedestrian 3.61 ERA. The Reds' 2015 second-round pick won't be rushed, especially after they added three veteran starters in the offseason.