The Chip Kelly era is off and running here in Philadelphia. Eagles fans have seen how his offensive scheme has affected Nick Foles, LeSean McCoy, DeSean Jackson and the rest of a unit that has been one of most prolific offensive attacks in the National Football League throughout the 2013 season. There are a lot of layers to Kelly's offense. Here, I want to take a close look at one facet that not only has been prevalent in Philadelphia, but has permeated its way throughout the rest of the NFL as well. We first saw it in Week 1 in the win over Washington on this 28-yard catch by tight end Brent Celek.

Let's take a look at the first phase of this play, as it starts with the staple run play in Chip Kelly's playbook: inside zone.

Inside zone is a basic "inside run" play that is designed to go between the tackles. It requires the offensive line and running back to work in concert to create an opening for the ball carrier to run to daylight. The Eagles run a wide variety of plays off of this inside zone look, but regardless of what they're running, it's always going to be the same steps for the offensive line, which ensures that the defensive front has to stay honest. McCoy will always be a threat in the run game, and defenses have to account for it.

The second phase of this play comes in the form of a "pop" pass to the tight end, who is running down the seam. When you have tight ends with the athleticism to work down the field, like Celek and Zach Ertz, this is another threat the defense must account for.

This is a simple, one-read decision for the quarterback. All he has to do is read the linebacker to that side. If he steps up to attack the run, the ball goes to the tight end in space. If he falls back to play the pop pass, the quarterback has the ability to give the ball to the running back. There is also a third option here, if all else fails ...

Look at the top of the screen, and you'll see the slot receiver running a bubble screen. If the quarterback doesn't hand the ball off, and decides that the tight end is not open, he has the ability to throw the bubble screen to the outside. The bubble screen is a huge part of the Eagles offensive attack, and has been since day one. On this play, Celek was wide open, and Michael Vick hit him for a 28-yard gain and an easy first down. This offense forces opposing teams to defend the entire field from sideline to sideline. There are rarely more than six players in the box defensively, which gives the offense the ability to run the ball efficiently and throw the ball to playmakers in space equally well.

That is one of the beauties of the Chip Kelly offense, regardless of who is at quarterback. He will almost always make sure the ball goes where the defense doesn't have the numbers. No matter what, you are always wrong as a defensive player.

Again, this is just one concept in the offensive playbook. There is a lot more that goes into it. However, since Week 1 teams such as Washington, the Cincinnati Bengals, Chicago Bears, Detroit Lions and others utilize this same exact concept as part of their offense. This scheme isn't a "trend" or a "fad," it has real staying power here in the NFL and will contribute to a lot of points for the Eagles offense in years to come.

Fran Duffy is the producer of the Eagles Game Plan show which can be seen on 6abc Sundays at 11:30 AM. Prior to joining the Eagles in 2011, Duffy was the Head Video Coordinator for the Temple University football team under former head coach Al Golden. In that role, he spent thousands of hours shooting, logging and assisting with the breakdown of the All-22 film from the team's games, practices, and opponents ...