Gray was drafted by the Rockies in the first round in 2013 from the University of Oklahoma. He spent all of 2014 with Tulsa in the Double-A Texas League, pitching decently enough with a 10-5 record, 3.91 ERA and a 113/41 K/BB in 124 innings with 107 hits. 2015 has been similar: 4.33 ERA in 114 innings for Albuquerque in the Triple-A Pacific Coast League, with a 110/41 K/BB and 129 hits allowed.
Keep in mind that the PCL and Albuquerque are difficult places to pitch and the stats are better than they may look on the surface. He's been quite effective recently, with a 20/6 K/BB and 1.20 ERA in 15 innings over his last three starts.
Listed at 6-4, 235, Gray was born November 5, 1991. On paper has the size and physical build to be a durable starter, but he's dealt with occasional arm fatigue since entering pro ball. In college he was clocked as high as 102 MPH but in pro ball he works at 92-95. That's plenty when his command is working, which it has been lately. Gray's secondary pitches are a slider and a change-up, both above-average to plus at their best, though his secondaries can be inconsistent. He tends to lose his release points when he is tired, costing him command of all three pitches, although this hasn't been a problem recently.
Gray profiles as a number two starter when everything is right, though the Colorado environment will test him.