PHILADELPHIA (AP) -- Teams that play the Philadelphia Eagles this season might want to spend extra time doing cardio work.
Chip Kelly has only shown flashes of his up-tempo offense in the first two preseason games and defenses already seem tired and confused while the Eagles are moving the ball with ease.
Just wait until the games count.
"I think we can go a lot faster," quarterback Michael Vick said. "I see what it does to a defense and the concepts and things that we do really puts this team in a position to succeed, but it has to be done right."
The combination of Kelly's faster pace with a new, balanced attack in which the Eagles run the ball far more than they ever did under Andy Reid is creating problems for opponents.
"It's so hard for defenses to get their calls in, because we are going so fast," running back LeSean McCoy said. "And, we are keeping teams off balance. When you run the ball that much, defenses don't know what's coming. Plus, we're so spread out, it can be a run play that turns into a pass."
Then there's the fatigue factor. Defenses, especially the linemen, are struggling to keep up.
"I got tired," Panthers rookie defensive tackle Star Lotulelei said after Carolina's 14-9 loss in Philadelphia last Thursday. "Just got to fight through it, get to the next play and keep sound fundamentals."
The first-team offense led by Vick and Nick Foles has four touchdowns on eight-plus possessions in two games. One drive ended with an end-zone interception and two others ended with fumbles.
And, it's only the preseason. The Eagles are still learning the nuances of Kelly's system and working out the kinks. Even the coaching staff is adjusting to Kelly's way of doing things.
"I think we as coaches are familiar with concepts but of course how we function as an offense, there was a lot that I learned," offensive coordinator Pat Shurmur said. "You know, I think I've always felt this, but I wish I knew now or I wish I knew 20 years ago what I know now. I learn something new every day, and I think if we function the right way, we have a chance to do good things."
In the preseason opener against New England, the Eagles started at faster-than-normal pace with Vick and then picked it up when Foles came in. They went to a hurry-up, no-huddle offense right from the start last week against Carolina with Foles starting and stayed with it when Vick entered in the second quarter.
Even the tempo in practice is getting quicker as players get more familiar with the offense and more plays are installed.
"Our operation has gotten smoother each practice, or each training session," Shurmur said. "I think we are a lot quicker than we were. I think back to when we first started doing this stuff in the spring, and we were moving at a snail's pace. Now I think we are not where we need to be yet. I think we would all like to play faster and faster and be efficient and run good plays. But I think we are much closer to where we need to be when it's time for the real games."
Vick said the Eagles showed less than one-third of their playbook vs. the Patriots and it wasn't much more against the Panthers. The vanilla approach is typical in the preseason, but it's clear the Eagles aren't running an ordinary offense.
"I don't think we've done a lot of complicated things, and I think part of that is not because we are not trying to show things but we want to make an evaluation of what our players can do and can't do," Kelly said. "Sometimes you complicate it too much, they are not allowed to play and show their true ability, because you've got them thinking too much. So I think that's part of what our process has been.
"Let's go out and play and see what they can do when we put them in situations."
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