Its because of where Gray was drafted and his build combined with his plus slider and fastball.  The Rockies do not have an ace (right now) and my first picks to pitch in the Wildcard game would be either Kyle Freeland or Chad Bettis. But if you're the #3 overall pick and you don't suffer a devastating injury, you're expected to have a chance to win 20 games with a sub-3.50 ERA every year.