Happy Friday, friends. Rather than doing a Digesting article about the Eagles today, I decided to look at the big question: is their offense a fad, or does it have staying power? Nothing gets football talkers more riled up than speculating on whether new tactics can work over the long haul in the NFL.

Most of them are of the default belief that nothing new can ever work. I’m sure that, in their early days, that was said about innovations like the 3-4 defense, or the zone-blitz, or the shotgun. The reality is that some new stuff works, and some of it is relegated to the dustbin of history.

And then you have something like the Run and Shoot, that worked well for a while, and then ostensibly faded away, but quietly, its principles are still quite common to this day.

Today, I’m going to explain why the Chip Kelly design works, and why it will continue to work in the NFL on an ongoing basis. Hit the jump, and we’ll get to the bottom of this.

So, there’s a thing called the “zone read-option” that some people are saying isn’t a thing anymore. Defenses figured out how to stop it! ZOMG! Why, just today, Pro Football Talk (talking about football isn't knowing about football) ran a story declaring it dead.

It’s easy to look at what Philadelphia is doing, and say that it’s the same thing that Washington or Seattle did last year. It’s not, though. That was about creating discipline conflicts in run defense, much like the Broncos did under the Shanahan regime, and the Texans do under Gary Kubiak. If you force a defense to be disciplined and stay at home in all eight gaps, it’s easier to win in the one gap in which you’re actually trying to run.

When Robert Griffin reads a DE at the mesh point, he can either hand the ball off to his RB going one way, or keep the ball and run at the gap that a crashing DE just vacated. There are two options there off the action, and a defense that sells out to fill all eight gaps can have some luck with slowing down those two options.

What if there were more than two options, though? What if there were five? Would a defense be able to cover them all? That’s the question that Chip Kelly is asking, and answering generally, no, you can’t stop everything.

Take a look at this diagram:

These are the options that Michael Vick can have off of one look, and one initial run action:

The HB (LeSean McCoy or Bryce Brown) runs the ball inside. This option is attractive when there’s a bubble over the B gap. The HB runs the ball outside. This is a good call when the defense has been failing to set the edge, or when they’re bunched inside after getting gashed by the inside run option. Vick takes the WR screen option. The Eagles love to stack receivers together to make it difficult for defenders in man coverage to get through the traffic. Vick runs the ball to the backside edge. This is the classic zone-read option, where if the backside DE crashes, the QB runs. We’ll talk about this momentarily. The TE releases vertically, and Vick makes a quick throw to him. All of those options can be done with the Chip Kelly design without Vick deciding which to take before the snap. Because the passing options (#3 and #5) are so quick, the offensive line can run block, and not be illegally downfield.

There’s also a sixth option, that does need to be called pre-snap, as a counter to the other five options:

6. Vick throws the ball downfield off of play actions. The offensive line has to pass-block here, which is why everybody has to be on the same page.

How does a defense guard against all six options? If you look at the numbered options in the diagram, you can see the challenge; the defense is stretched both vertically and horizontally. How can you defend every inch of the field?

We’ll get to that, but before we do, I want to make sure everybody knows a few things:

This is fundamentally a scheme that’s trying to run the football, as a basis for everything else that they want to do.

It’s an extremely well-conceived running scheme.

We hear all the time that the NFL is a passing league, and that the trends increasingly skew that way.

When defenses are staffing up to stop the pass, being contrarian, and being good at running the ball offers a big edge against defenses that aren’t built to stop that kind of offense.

The scheme is in place in Philadelphia, for the most part, but the ideal players to run it aren’t necessarily there yet. Wait a year or two before you pass too harsh a judgment.

The Chip Kelly offense goes beyond the simple zone-read stuff, because it creates run-pass conflicts for defenses. All but the very best ones are going to have to try to guess right, snap after snap, and that makes them vulnerable.

Here’s what you have to do to stop each of the six options:

The HB (LeSean McCoy or Bryce Brown) runs the ball inside. Your interior defensive linemen have to be able to win their matchups inside, preferably by two-gapping. Four absolutely must beat five, or the defense is in big trouble. The HB runs the ball outside. The defense has to consistently set the edge on what I’ll call the action-side (the side opposite where the RB aligns pre-snap). Whether the guy marked “S” is the Sam linebacker or the strong safety (I would propose to mix that up against the Eagles), he must be able to react quickly, and set the edge, funneling the runner inside. Vick takes the WR screen option. The corners are going to have to play press technique all game, whether they play man or zone coverage, and they all must be able to defeat blocks by WRs and make a tackle. Vick runs the ball to the backside edge. Either the backside DE can stay at home, which is a good way to get a QB not to keep the ball, or he can crash, and get the QB to run it. A guy like Vick can obviously hurt a defense, but what DCs have started to do is to scrape-exchange on the backside. That means the backside DE (let’s say Robert Ayers) crashes, inviting Vick to keep the ball, and he runs the ball, right into the WLB (Danny Trevathan), who has looped outside of the crashing Ayers, into the QB run lane. It’s basically like a stunt for a different purpose, and if it works right, Trevathan might get to take a big shot on Vick. You know that play where Wesley Woodyard got the big shot on Terrelle Pryor on Monday night? That was scrape-exchange at work; the DE crashed, and Woodyard looped around from the inside to the outside. The TE releases vertically, and Vick makes a quick throw to him. This is a constraint play that forces the guy marked 'S' to hesitate and think about covering the TE: If he’s crashing hard on the outside run game, the TE should be wide open. If he’s too worried about covering, McCoy should be able to get out to the edge. The answer to this is to coordinate with the FS when the action-side force player (S) is crashing, and when he’s covering. You can get away with him crashing some, and passing the TE off to the FS in man coverage. (Then you have no deep safety, and you’re playing Cover 0, which is risky.) Vick throws the ball downfield off of play actions. Your corners had better be able to hold up in single coverage, because at most, they’ll have one safety deep, and sometimes, it’s likely to be zero.

That’s pretty difficult, right? The Chiefs did a pretty good job of checking all six boxes at times in their win last Thursday, and they still gave up 465 yards of offense, including 264 on the ground. How will the Broncos fare? It will probably be a mixed bag, but here are some thoughts:

The Broncos have a rare four-man defensive line that can win against five blockers. That will be vital to slowing down both the inside and outside run. The LBs are fast and physical, and that will help with handling the run game as well, including scrape-exchanging on Vick. The CBs have to play press coverage, and they must tackle the screen game. When they play man (which they mostly will) they have to be as sticky as the Chiefs’ guys were last week. The Eagles WRs really struggled to separate, and it was probably the biggest downfall of the team. You know how normally the nickelback and the Sam LB switch off based on the offensive personnel grouping? Well, the Eagles will play almost all 11 and 10 personnel, so the nickelback will have to be on the field almost every snap. I propose to swap Duke Ihenacho and Nate Irving situationally, and to have each crash the edge sometimes, and each player to cover the TE sometimes. Rahim Moore needs to be terrific, because he’s needed everywhere against this scheme. He’ll have to play as a single-high safety at times, and as a man-coverage guy at other times. He has the ability to do what’s needed, but not always the consistency. We need to see big-time play throughout the game Sunday. The Broncos are best at playing man coverage, as I’ve mentioned, but they played a lot of zone last week. I was confused as to why at the time, but after watching the tape, I think that it was mainly to prevent Terrelle Pryor from running wild on the ground. There also was probably some element of trying to protect Kayvon Webster when Tony Carter went out of the game with injury. Anyway, Vick ran for 99 yards on four carries against the Chiefs’ man coverage, mostly on scrambles off of called pass plays. The Broncos have to spy Vick in the passing game, if they want to play man. Retired for John Elway. (TYJE) When you're playing the run first, pass rush is a challenge. In those situations, the defensive linemen need to prioritize staying in their lanes, to avoid the big scramble by Vick. The best thing the Broncos can do is get up 14 or 17 points, and force the Eagles to play the dropback game to try to catch up. If you do that, you’ve got them beat, because Vick has never had the precision or anticipation to beat a good coverage scheme. He’s excellent against a misdirected/confused defense, and below average when the defense knows that he’s throwing.

That’s what I’ve got, friends. It will be tough to stop the Eagles offense, but I think the terrible Eagles defense will have twice as big a challenge with the Broncos offense.