As much as coaches and players love to gloat about how far ahead all of their players are in their rehab schedules, no one truly knows how a player is going to react when the lights are on and the speed of the game is cranked all the way up.
Truth is, players who recover from devastating injuries and turn out to be stronger than ever, such as Adrian Peterson and Wes Welker, are from a rare breed. Between Rashean Mathis and Stewart Bradley, plenty of former stars who sustain catastrophic injuries wind up in the black hole of irrelevancy in no time in the "Not For Long" league.
Here are 10 players that will cause both long- and short-term concerns for their respective teams as they try to get ready for the 2013 season.
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