The Rockies selected Sullivan's contract from Triple-A Albuquerque ahead of his start Friday against the Athletics.
Sullivan will be making his MLB debut Friday, though he will be doing so in a very hitter-friendly environment at Las Vegas Ballpark after posting a 5.76 ERA and 1.57 WHIP in 54.2 innings at Triple-A, making him a less-than-desirable fantasy option. Sammy Peralta was optioned to Albuquerque to make room for Sullivan on the active roster, and Chase Dollander (elbow) was moved to the 60-day IL to free up a 40-man spot.