Ask offensive linemen if they prefer run blocking to pass protection, and the majority will choose the former.

"Pass blocking is not fun," Eagles center Jason Kelce said Sunday. "You have to sit there and wait for a big, 300-plus pound man to come at you. Whereas in a running game, you're the aggressor, and you get to go at them."

Kelce used a boxing analogy to compare the two disciplines. Naturally, he compared run blocking to the style of a great Philadelphia fighter.

"Pass blocking is like Muhammad Ali," Kelce continued. "You're kind of ducking and dodging and waiting for the defensive guy to tire himself out, whereas run blocking is the Joe Frazier. You're kind of just trying to come at him with a haymaker and knock him out."

Chip Kelly's offense, or at least what we know of it thus far, throws more jabs than uppercuts. The up-tempo portion is designed to methodically move the chains with runs and quick-hitting passes. If a runner or receiver breaks one, then so be it.

But Kelly's scheme, which produced a 60-40 run-pass ratio at Oregon, is run-based.

Does that mean the Eagles will have a similar proportion? Probably not. In the first two preseason games, the ratio was about 43-57. That's a fairly significant reversal, but it's still nowhere near the pass-heavy imbalance the Eagles had under Andy Reid.

"This offense in general is designed to be successful in the ground game," Kelce said. "And for an offensive lineman, that's what you love."

If running the ball more meant happier and more productive linemen, then every team around the NFL would stay on the ground. But there's a reason why the league has been tilting toward the pass - it works. It's not like there aren't great lines around the league that have to pass protect the majority of the time.

But Kelly's scheme is designed to spread the defense and to run the ball when the offensive line has favorable blocking numbers. As long as everyone does his job and blocks his man - and there is enough talent on the Eagles line to expect as much - there should be room to run.

"Everything's designed to give the running game the upper hand wherever you're going with it," Kelce said. "We feel very confident that as long as we have numbers, as long as we're hat for hat, we have a good enough offensive line to capitalize against whoever we're playing."

Even without Jason Peters at left tackle, the starting line has looked very solid in two preseason games. Quarterbacks Michael Vick and Nick Foles have only been sacked once apiece, running backs have averaged nearly 5 yards a carry, and the pocket has been consistently clean.

"I think we're running a good balance right now," guard Todd Herremans said. "A lot of times in the last couple of years our pocket would collapse because we would get into a situation where we would have to throw the ball. We were basically walking up to the line saying, 'Hey, we're throwing right here, try to get past us.' "

Not only is there more balance, but Kelly's "packaged" plays, in which the quarterback has run-pass options, keep the defense guessing. And those plays call for the line to run-block, even if the quarterback opts to throw a short pass.

It's all part of Kelly's up-tempo offense, which is designed to keep defenses off-kilter.

"It gets us tired, too," Herremans said. "We're out there sucking gas just like the defense is. But the biggest difference is they're so tired about getting lined up, and we know what we're doing. So when you're tired, the advantage is going to go to the person that knows what they're doing."

Kelce and Herremans were cautious not to get ahead of themselves. When a reporter said that the unit was playing "great," Herremans responded, "Great?"

Compared to last year, though, it has looked great.

Rookie Lane Johnson has had a seamless start at right tackle. Allen Barbre has done solid work in place of Peters. And Kelce, Herremans, and guard Evan Mathis are rounding into form after surgeries.

Peters, who missed all of last season with a ruptured Achilles tendon, has yet to play. If he can return to anywhere near his 2011 all-pro level, it will be a significant upgrade over last season, when Kelce and Herremans also suffered season-ending surgeries.

"Hopefully, all of us keep standing this year," Mathis said. "We know we have potential, but that doesn't do [squat] for you if you don't go out and execute and work your butt off."

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