PHILADELPHIA — Chip Kelly's star receiver at the University of New Hampshire had a standard comeback when a defensive player talked trash.

Recalled record-breaking pass catcher David Ball: "Whenever they would chirp, the only thing I would say back to them was, 'I don't even know who you are. You're not even on my scouting report. We don't even have a scouting report. We worry about us, and we beat you. That's how it works.'"

The response is illuminating not because it reveals what type of offense Kelly will run as first-year coach of the Philadelphia Eagles — the league's biggest mystery heading into the 2013 season — but the attitude Kelly has instilled in his players since he was offensive coordinator at New Hampshire from 1999-2006.

"We didn't even notice [defensive players] until we were in the end zone — to us, they were simply something in our way," said Ball, who caught 58 touchdown passes, shattering the NCAA Division I-AA career record of 50 held by future Hall of Famer Jerry Rice. Ball was briefly with the Eagles this summer, helping fill out the depth chart at receiver after Jeremy Maclin's season-ending knee injury.

"We didn't know their names, we didn't know their number," Ball continued. "The only thing we cared about was what the play was, what our signal was, and executing it. . . . They were just a facade, bags to run away from. That speaks to [Kelly's] core philosophy that we're going to worry about us and perfect us. Because I believe in us. We're not going to tailor us every week to somebody new because we're fearing what they do. We are going to make people fear what we do."

There's no overwhelming fear of the Philadelphia Eagles in the NFL. The franchise is coming off a 4-12 season and hasn't won a playoff game since 2009. Kelly is still deciding on a starting quarterback, with Michael Vick and Nick Foles battling for the job, and rookie Matt Barkley the apparent third-stringer. All signs point to this being a rebuilding season.

But there is a great deal of curiosity as to what type of offense the innovative Kelly will run, and whether he can transport to the pros the up-tempo style he used at New Hampshire and later as the wildly successful head coach at Oregon.

"I think Chip Kelly is going to have as much influence on the game and the way it's played now as anyone," Hall of Fame coach John Madden said. "If for no other reason, just the pace of the game and the number of plays.

"Everyone talks about it: Can Chip Kelly do what he did in college? Probably not in its entirety, but he can do a lot of it. Not only that, everyone else is going to do a lot of it."

Kelly's practices at training camp this summer have looked different from those elsewhere in the NFL. They are like track meets, not just because Eagles players are running more than most but because there are "events" constantly taking place on side-by-side fields. While giant speakers blare all types of thumping music — Kelly prefers that to simulated crowd noise — the team is divided into position groups throughout most of the practice. There is less seven-on-seven and 11-on-11 work than at typical NFL practices.

"When you're running a no-huddle, high-tempo offense, the amount of opportunities you have to get things ironed out at practice triples, quadruples," Ball said.

Another benefit, he said, is that Kelly's teams cycle through plays so quickly in practice, they tend to be in better shape than opponents.

"So even when [opposing teams] try to get a practice squad to simulate that speed, good luck," he said. "Because it's their first time doing it. There's a lot of perks to the efficiency of what Chip does."

One drill that is particularly eye-catching has five quarterbacks lined up side by side, each simultaneously throwing to one of five receivers, all running different routes. It's an unusual sight, seeing five footballs cross paths in the air, and not a drill that's common around the league.

No one outside the Eagles can say whether these differences mean anything, or whether Kelly will truly break away from the pack in a league whose offenses (and practices) are starting to look a bit more like the wide-open college game.

"I talk to coaches now, and the number of plays that they get in in practice has doubled or tripled," Madden said. "Part of it is the CBA [the collective bargaining agreement, which significantly limits how much time coaches can work with their players in the off-season], part of it's the way they're scheduling it now, and part of it is Chip Kelly and that up-tempo football.

"No one, including Chip Kelly, is going to take his whole program and put it in the NFL. But they are going to take a hell of a lot of parts of it."

Great football minds can disagree on the topic. Jon Gruden, the Super Bowl-winning coach and now an ESPN broadcaster, downplays the influence some predict Kelly will have on the pace of the game.

"If I read one more article about Chip Kelly's tempo, I might throw up," Gruden said. "Chip Kelly didn't invent the no-huddle offense. I've got a lot of respect for Chip Kelly, the reason is because of what he did at New Hampshire as an offensive coordinator. Forget the no-huddle for a minute. The guy knows offensive football."

When Gruden was coach in Tampa Bay, he asked his staff to not only scout players but to scout assistant coaches in case the Buccaneers had an opening down the road. His father, Jim Gruden, was among those sent out to scout coaching talent.