Santillan has been dominant at Double-A Pensacola since his promotion, including a 5.2-inning scoreless outing Monday night where he struck out 11 batters, the Reds' official site reports.
Overall, Santillan has a 1.84 ERA in five outings for Pensacola over 29.1 innings, with a 32:7 K:BB ratio and just one homer allowed. RotoWire rates Santillan as the Reds' #8 prospect.