Cowboys coach Jason Garrett told reporters on Tuesday that Darren McFadden recently had surgery on a broken elbow he suffered in an accident at his home. McFadden is out for a couple months, and may or may not be ready for Dallas' season opener against the New York Giants in September.
If there was ever much doubt, this should cement Ezekiel Elliott's status as the RB1. Alfred Morris will likely serve as Elliott's backup as long as McFadden is sidelined. Rookie running backs who are drafted in the early rounds of fantasy drafts tend to outperform their veteran counterparts, but no rookies in recent memory have been drafted as early as Elliott is being drafted this year (in the 1st round).