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Green Bay Packers coach Mike McCarthy wasn't among the skeptical crowd when Philadelphia Eagles coach Chip Kelly left Oregon before the start of last season to join the NFL.

McCarthy was always impressed with Kelly's offensive system. It's based on high tempo and piling snaps on top of each other, something McCarthy has tried to instill with the Packers in recent seasons.

"I've always liked the concepts," McCarthy said. "It was just interesting to see how he was going to use the personnel, and I think he's done a great job of it."

So far, the transition from college to pro football has been seamless. Kelly has led the Eagles to a 17-8 record – including a NFC East title last season – entering Sunday's game at Lambeau Field. His offense has been dynamic and explosive, not unlike his former Oregon teams.

The Eagles rank fourth in the NFL with 31 points per game, second with 71.2 plays per game are second, and fifth with 404.3 yards per game.

"It lends itself to being friendly for all the positions, not just the quarterback," said Eagles quarterback Mark Sanchez, replacing injured starter Nick Foles. "I think the guys really enjoy all the tempo stuff. You've got to be in pretty good shape to do it. I've got to get some extra running in every week, just to make sure I can keep up with everybody and I'm not holding us back. It's a fun system for all of us."

Green Bay's defense struggled in a 27-13 home loss to Philadelphia last season. Foles had three touchdown passes. Running back LeSean McCoy had 155 rushing yards. The Eagles racked up more than 400 yards of offense.

Of course, Scott Tolzien was the Packers' starting quarterback in that game, which came one week after Aaron Rodgers broke his collarbone against the Chicago Bears. Sunday, the Eagles will be the team without their starting quarterback.

While at UCLA, Packers defensive end Datone Jones played against Kelly's Oregon teams. He joked Wednesday he doesn't have too many good memories from their matchups. Indeed, Oregon beat UCLA by at least one touchdown in each of Jones' three matchups against the Ducks.

On film, Jones said the Eagles' offense looks familiar.

"It's the same thing," Jones said. "It's fast. They run pretty much the same plays, and it's quick. That's what gets you. You've got to be in shape, you've got to be disciplined, you've got to get down, and you've got to get going."

Even if circumstances will be different when McCarthy and Kelly meet again Sunday, the lessons from last season remain. McCarthy knows where the Eagles' offense can hurt his defense. What's the hardest part about slowing Kelly's system? What challenges does their tempo present?

This time, McCarthy believes his team will be ready.

"I think it's something we're definitely accustomed to," McCarthy said. "The biggest thing that's stressed, I wouldn't say it's a position. They're stressing your communication. I mean, your communication has to be distinct because you have to be exact, and you've got to stay in clean defenses."

-rwood@gannett.com and follow him on Twitter @ByRyanWood

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