McMahon was promoted to Triple-A Albuquerque on Friday, Nick Groke of The Denver Post reports.
In his second season with Double-A Hartford, the top prospect showed that he had mastered the level, slashing .326/.390/.536 with six home runs, 28 runs scored and 32 RBI in 49 games. He also added seven steals and learned a new position (second base), pushing the Rockies to advance him up the organizational ladder. McMahon drastically improved his strikeout rate with the Yard Goats this season (19 percent), and if he can keep it up with the Isotopes, his added positional versatility could make him a candidate for a call to the big leagues toward the end of the season.