His minor league stats.
2008 9-2, 3.20 ERA, 1.258 WHIP
2009 8-14 3.36 ERA, 1.15 WHIP
2010 15-8, 2.21 ERA, 0.983 WHIP
2011 10-12, 2.46 ERA, 1.023 WHIP
2012 14-7, 1.53 ERA, 0.994 WHIP
2013 15-7, 2.10 ERA, 0.962 WHIP
Even with those numbers, he's projected to be a #4 pitcher.