All-22: How the Eagles Lean On Cover 3

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If you’ve missed this publication the past two years, it’s a comprehensive look at the season ahead with contributions from a variety of talented writers.

There are also some untalented writers who are allowed to pen chapters. That’s where Tim and I come in.

My piece this year focused on the defense as a whole. What did Billy Davis run in his first year as the Eagles’ coordinator? What were the strengths and weaknesses? What changes are in store going forward?

Below is part of what I wrote, focusing on one of the Eagles’ primary schemes on the back end: the Cover 3.

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Where the primary issues surfaced on defense was through the air. The Eagles finished 25th in passing defense DVOA and relied on takeaways (19 INTs) to stay afloat.

“We played basically a traditional three-deep and quarters type coverage, and then quarter-quarter-half zone coverage,” said defensive backs coach John Lovett. “[Those] were our main calls. And then on third down, we tightened things up. We played some different forms of man coverage. If you look back in a nutshell as far as what we did, it would fall into those general categories.”

The one coverage the Eagles went to over and over again (specifically on early downs) was the three-deep zone, or Cover 3. That featured three deep defenders (two cornerbacks and a safety) splitting the field into thirds and four “rally” defenders (usually two inside linebackers, an outside linebacker and a safety) underneath.

Here’s an example of the Eagles’ Cover 3 from the playoff game against the Saints:

Cary Williams and Bradley Fletcher are the corners. Nate Allen is stationed deep.

The cornerbacks’ jobs in this coverage are to not let anything get outside of them or behind them. The deep safety’s job is to patrol the middle of the field. When played correctly, post routes, corner routes and vertical routes outside should be taken away.

“You gotta have zone eyes in our Cover 3s, and we’re responsible for our deep third, making sure we can see our No. 2 receiver to our No. 1 receiver and sort out the routes as they come,” Fletcher said.

The number system Fletcher uses refers to the alignment of the receivers to each side of the formation. The receiver closest to the sideline is the No. 1. If there’s a slot man, he’s No. 2. And so on.

While Cover 3 is a zone defense, it has man principles. Chip Kelly often talks about “plastering” to receivers after the routes express themselves.

“Once routes get down the field, it turns into man at the end of the day,” Fletcher said. “At first you have to sort out the routes.”

Some defenses, like Seattle’s, will have the corners press receivers at the line of scrimmage and then bail into their deeper thirds. But that technique can only be used if the personnel fits. Eagles cornerbacks often played off and retreated right away.

The deep safety, meanwhile, is asked to overlap his zone with those of the cornerbacks.

“I’m in the middle of the field so I’m protecting the corners on post routes,” said Malcolm Jenkins, who admitted he did not play a lot of Cover 3 in New Orleans. “I’m protecting inside players on verticals by your tight ends and wide receivers. But at the same time, somebody like me, I get a little nosy and I like to try to rob some things when I know my corners can lock down their sides, and then I don’t have to babysit them. You can make a lot of plays, especially off tipped balls and overthrows. You’ve just gotta find a way to get around the ball.”

Jenkins’ nosiness could be a welcome addition to the defense. The example in the image here ended up being a 21-yard completion to TE Jimmy Graham. All season long, Davis stressed to the defensive backs to play deep to short. Oftentimes, that ended up meaning playing conservative and allowing gaps in their zone defenses.

The Cover 3 is naturally going to be vulnerable against throws down the seam, and the underneath defenders failed to get their hands on Graham at the line of scrimmage in this example. But take a look at how deep Allen is playing. He has no chance of getting to the ball in time to break up the pass or deliver a big hit.

Asked what width the safety is responsible for, assistant defensive backs coach Todd Lyght said: “It’s basically 4 yards inside each of the numbers from 4 yards inside each of the numbers. But we like our players to play overlapping. Obviously when you take great angles to the ball and you play with speed and you play with knowledge, then you have an opportunity to do really, really well.”

One weakness of the Cover 3 is that it allows offenses to complete underneath passes with relative ease. If a defense were committed to playing Cover 3 for an entire possession, a quarterback could dink and dunk his way down the field.

“The thing with Cover-3 is everybody has to know the weakness is underneath,” Jenkins said. “And that’s where we want them to throw it. So if they throw a 5-yard route, we just make the tackle and we live with that. That’s what we’re giving up. What we don’t need to do is get nosy on those short underneath routes and then you open up the seams behind it.

“Then you put the safety in position where he has to drive. And now you’ve got these posts coming behind your safeties. So if everybody’s playing top down, you may give up some yards on checkdowns and it may look bad on the stat sheet, but that’s what you’re playing for. You’re playing to take away the deep routes and make them check everything down.”

The underneath defenders split the field into four zones. The two outside guys play the curl to the flat. They will sometimes be tasked with starting up near the line of scrimmage, showing pressure and then retreating to their zones.

“It’s a harder drop for the linebacker because we start on the line,” Connor Barwin said. “We have to go all the way from the line of scrimmage at usually a 45-degree angle, and we have to get 12 yards deep. So the hardest part is getting your depth. And then you’re curl to flat, so usually you’re departure angle is about 1 or 2 yards inside the No. 1 receiver. And then you just read where he goes.”

The underneath defenders are known as “rally” players. Their jobs are to rally to the football and finish tackles, limiting the damage after the catch on the short, high-percentage throws. The cardinal sin for the curl/flat defenders is not getting enough depth, noted Barwin.

Meanwhile, the hook/curl defenders patrol the middle of the field underneath.

“Most of the time [when] we play zone drops, some aggressive defensive coordinators like to hug you up 8 yards, 10 yards [from the line of scrimmage],” said inside linebacker Najee Goode. “And then some guys like to play deep, 10 or 15. Depending on what we see on different opponents, we might do either/or. You’re playing inside the hashes or outside the hashes depending on what the formation is. You’ve got three guys over top of you so you can let guys run underneath and kind of get… those big highlight hits you see.”

Davis loves having his inside linebackers threaten the A-gaps to either side of the center at the line of scrimmage. The overall scheme counts on bringing pressure from different areas and disguising looks before the snap. By showing the inside linebackers in the A-gaps, the idea is to force the offensive line to account for them in protection, even if they eventually end up dropping back.

Like the curl/flat defenders, the hook/curl players can’t get greedy. They have to get enough depth. If a pass is completed in front of them, they rally and make the tackle. If they cheat up and allow a pass to be completed behind them, the scheme breaks down.

There are other vulnerabilities as well.

“I think obviously the seam routes are gonna expose that a little bit, especially with play-action pass where the second-level defenders aren’t able to carry the seam route,” Lyght said. “Also the dig routes. Play-action pass is gonna hold second-level defenders all the time, so as a defensive back and as a former player, you have to be able to drive aggressively on those routes, knowing that your safety’s gonna be able to back you up if there is a dig and up or a double move.

“Every defense has vulnerabilities, but the key for us as coaches is to explain the vulnerabilities of the defense, explain the strengths of the defense and get the players to understand and comprehend what the strengths are and what the weaknesses are and how the offense is gonna try to attack every defense.”

By all accounts, the Eagles are going to continue to play a lot of Cover 3. They are counting on two different factors to produce better results. One is continuity and familiarity with the scheme. Two is Jenkins at safety instead of Patrick Chung.

“The spacing is what is 10 times better now than it was a year ago,” Davis said. “Understanding where your spot is in relation to the guys on your right and left and how that fits together. And playing deep to short. We know that there is some error in that coverage. We know that. We make it that way. So I think the spacing is better in our zones.”

There’s room for improvement in every area of the Eagles’ defense, but plenty of resources this summer will be devoted to making sure they generate better results when playing Cover 3.


Thanks to our friend Coach Flinn for his help on this post. Be sure to give him a follow on Twitter.