Castillo (0-1) struck out eight Monday, but allowed four runs on nine hits and a walk over 5.2 innings in a loss against Colorado.
Castillo continues to show exceptionally nasty stuff. He induced 17 swinging strikes on 111 pitches and now has 22 strikeouts in just 16.1 major league innings. He has been too wild to go deep in games, however -- even though he walked just one batter Monday, he threw only 10 first-pitch strikes to 27 hitters, which contributed to the whopping nine hits he allowed. But Castillo is young, and if he can tighten up his control, his already electric arsenal will prove all the more effective.