Tommy Lawlor wonders if Dion Lewis might be the guy to break Marty Mornhinweg's constant dependence on a single running back:
Dion Lewis could be the RB to change all of this. The key is that he’s not just a runner. Dion, based on this summer, looks like he could be a weapon in the passing game as well. He must show that he can be counted on as a blocker. For those who might compare him to Ryan Moats because both guys are small, don’t. Lewis is already an infinitely better blocker than Moats was.
I agree with Tommy that the Eagles need to spread the load around where possible. Running backs just don't last long in the NFL, and the more you can rest them, the healthier they'll be. However, the problem with Lewis is that he's essentially a (very) poor man's version of McCoy. Even if he's as good as recent reports out of training camp suggest, Lewis will always be worse than McCoy at pretty much every phase of the game. Thus, having him replace McCoy is always a loss for the offense.
I think one of the reasons Correll Buckhalter was a good complement to Brian Westbrook is that he could do many of the same things, but had a different style and different strengths. It's (similar to) a comparative advantage problem.