Four other running backs aren't promised as much, and it's not for a lack of effort.
Henry Josey, Matthew Tucker, Chris Polk, and Kenjon Barner all have displayed outstanding qualities at different times, and could all benefit the speedy, high-energy offense that Chip Kelly insists on running.
No NFL team, to anyone's knowledge, would carry six running backs. Five is almost as much a stretch. Four seems to be the prime number for an Eagles team that values versatility in its zippy weapons.
The question remains: which of the back-ups would have the best shot of joining McCoy and Sproles on gameday?
Tucker was Squad'ed for most of last season, before being activated for a pair of games. Tucker did impress last summer, but the sizable back (6'1, 227) has turned more heads this year, running for 86 yards on 18 carries (4.78 YPA), scoring a whopping four touchdowns across two games.
Tucker has a quick burst off the snap and through the hole, demonstrated behind the impressive second-string offensive line. Tucker prefers going left, with Andrew Gardner and Matt Tobin leading the way. His lone blight was a careless, untouched fumble against the Bears two weeks ago.
Polk has yet to see any action this summer, thanks to a hamstring tear. The stocky back (5'10, 224), when he is healthy, draws some comparisons to Duce Staley with his upper-body drive and fleet-footedness.
Polk took 11 hand-offs last season, rushing for 98 yards and three touchdowns. His most notable performances were against the Broncos, where he scored two touchdowns, and in the snow game against the Lions, as he helped the Eagles polish the afternoon off on big runs.
A questionable holding call erased a 70-yard touchdown run last night for the undrafted rookie out of Missouri. Had it stood, Josey would have run for 174 yards on 13 carries this summer, and a whopping 13.38 YPA average.
As it is, the compact runner (5'9, 194) has still run for 104 yards on a mere 12 carries across two games, and shows no signs of the devastating knee injury that threatened his career three years ago. Durability was a concern in drafting him, but as a contributor behind McCoy and Sproles, he could end up a fine niche player.
Kelly can't resist bringing his former Ducks on board, and traded a seventh-round pick to acquire Barner from the Panthers just days ago. Roughly the size of Josey (5'9, 195), Barner doubled as a track sprinter in college, so straight-line speed won't be an issue.
The downside to Barner is roughness in his special teams play, and has shown to be merely an average returner. He did receive seven carries in his Eagles debut, rushing for 32 yards (4.57 YPA), but if he ends up an odd-man-out in this overloaded backfield, he's Practice Squad eligible.
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