On Eagles backup running backs

I get questions about who will back up LeSean McCoy as running back for the Philadelphia Eagles. The two-part answer is (a) Dion Lewis and (b) yes, if McCoy had to miss time they'd be in big trouble. But there is a lot of interest around two rookie running backs in Eagles camp -- seventh-round draft pick Bryce Brown and undrafted free agent Chris Polk. It's possible only one makes the team. It's possible one or both someday overtakes Lewis for the backup role. Lots of things are possible.

When I was there last week, Brown looked like the better runner and Polk the better pass protector. To read Sheil Kapadia, Polk is an otherworldly pass protector:

During this afternoon's session, the undrafted free agent out of Washington sent cornerback Brandon Hughes flying on a blitz pickup that drew perhaps the loudest ovation of the day.

"I actually messed up on that play, because I went to the wrong side," Polk said. "But I knew he was coming so I just had to get back there quick. I don't want the quarterback getting hit on my behalf, so that's something I try to hang my hat on."

Earlier in practice, during one-on-one blitz pickup drills, Polk (5-11, 215) stoned free safety Phillip Thomas, eventually pinning him to the ground.

Given Polk's skill set and the Eagles' current roster makeup, let's think outside the box for a moment: Could he be this team's answer at fullback?

It's an interesting idea, but I can't speak to how realistic it is. What's more interesting to me is the importance the Eagles place on pass protection when determining the roles of their running backs. If the backup's more significant role is to protect the quarterback because they'd have to throw a lot more with McCoy out, that's the kind of thing that could swing things in Polk's favor.