Looking more in depth at Darrelle Revis’ ACL comeback (why so many NFL players don’t make it back)

In a recent profile of Darrelle Revis in Sports Illustrated, Revis mentioned the difficulty he had coming back from his reconstructive ACL surgery. He was injured in September 2012, and didn’t start running again until May 2013.  -> I don’t know what they mean by running here. Straight line, light running typically takes place within a few months post-op. […]