McCoy strained his hamstring during an evening joint practice with the Cleveland Browns. He limped off the field during the session, leaving Buffalo paper thin in the backfield.
Rookie Karlos Williams -- a leader for the No. 2 role -- is out multiple weeks after undergoing what Bills coach Rex Ryan called a "sensitive" procedure. Veterans Fred Jackson (hamstring), Boobie Dixon (calf) and Bryce Brown (hamstring) are also sidelined, leaving non-household names Bronson Hill and Ricky Seale to carry the rock.
With McCoy a candidate to lead the AFC in carries this season, the Bills aren't going to rush him back into action. It's bubble-wrap time until September dawns.