When the Eagles used their first-round pick on offensive lineman Danny Watkins, the obvious assumption was they wanted to improve protection for Michael Vick.

And that's true.

But a question we've yet to explore (at least here) is how Watkins will impact the Eagles' running game.

And specifically, how he will impact LeSean McCoy, who broke out in his second season, averaging 5.2 yards per carry (yes, this was before he became a Twitter Gangster).

McCoy accounted for seven runs of 20 yards or more, which ranked tied for 14th. But no player had more runs of 40 yards or more (five).

With Jerome Harrison likely headed for unrestricted free agency, the Eagles could be in the market for a backup running back, even though they drafted Dion Lewis out of Pittsburgh in April.

I went back and looked at McCoy's seven runs of 20+ yards, and several things stood out.

For starters, five of the seven were designed inside runs. In other words, they were not pitches to the outside where McCoy turned the corner and sped up the sideline, although there were exceptions (most notably, the 50-yarder against the Giants).

Five of the seven runs were also out of single-back formations. Only two of them came out of the I-formation with a fullback, Owen Schmitt. On one of the plays, Schmitt delivered a nice lead block and McCoy scampered 62 yards against the Colts. On a 40-yard gain against the Giants, McCoy didn't follow Schmitt's block, but found a different lane.

Looking ahead to 2011, the Eagles still have Schmitt on the roster, and they drafted Stanley Havili out of USC in the seventh round. Schmitt's the favorite to be the fullback, but he didn't play so well last year that he's a lock to win the spot.

The ESPN.com splits show McCoy was better running to the left than to the right. On carries to the left, he averaged 5.8 yards per carry; up the middle, that number was 5.1; and to the right, 4.4. The big runs followed a similar pattern. Todd Herremans delivered several outstanding blocks on the big runs, and Jason Peters had a hand in a few too. As we've discussed before, the Eagles' two best offensive linemen were on the left side.

But the guy that surprised me when re-watching the runs was Mike McGlynn. He was a key on several of the big runs. In Week 2 against the Lions, McGlynn and Nick Cole double-teamed a defensive tackle as McCoy picked up 46 yards. Against the 49ers, McGlynn's block created a cutback lane for a 29-yard run. I also noticed him on the 62-yard run against the Colts; a 40-yard run against the Giants; and the 56-yarder against Dallas.

With the selection of Watkins, McGlynn might be the odd man out on the Eagles' offensive line. Will he get a chance to compete at center with Jamaal Jackson? Or will he be the first backup off the bench at all three interior line positions? As we've seen in years past, depth along the line is critical. McGlynn would be a very valuable reserve for the Eagles in 2011. After next season, though, he's a free agent, and based on last year, he certainly looks capable of starting somewhere. Remember, he's only 26.

And finally, credit to McCoy - great vision and elusiveness throughout. Against the Colts, the run was designed to go outside, but he cut it up the middle and made two defenders miss.

The 50-yard run against the Giants came at a critical time with the Eagles trailing by one and less than five minutes left. And in the second Giants game, he broke a tackle at the line of scrimmage before picking up 20 yards.

If the Eagles do look for a running back to complement McCoy, it'll be interesting to see what kind of player they target. I don't think they need a big back. McCoy proved his toughness last year and converted 8 of 10 third-and-short opportunities.

I would guess the Eagles would be looking to add a back who has speed, can catch the ball and pick up the blitz. As a team, the Birds had 428 rushing attempts in 2010, which tied for 15th in the league. But 100 of those were courtesy of Michael Vick. Take his attempts away and the Eagles would have ranked second-to-last to the Cardinals in attempts.

In other words, McCoy's backup is not going to get a lot of work. The Eagles need someone who will be happy with only a handful of touches a game, but also someone who can step in and carry the load if McCoy gets injured. That's why I don't think Reggie Bush makes much sense, but then again, I'm not sure many running backs around the league really fit my description.

Once the lockout ends, we can take a look at the free agency list and see which ones might make sense.

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