There were a lot of absurd stats put up during the 2019 NFL season, but none of them could match the absurdity of the Patriots defense allowing only two passing touchdowns and recording 19 interceptions over the first half of the season.
New England’s pass defense wasn’t quite as dominant over the second half of the season (against a far tougher schedule) but finished 2019 leading the NFL in just about every efficiency metric out there, including Expected Points allowed and DVOA, as well as more traditional (or dumb) stats like passer rating and yards allowed.
It’s easy enough to just say, “Bill Belichick, still a genius” and move on. But considering just how dominant this defense was despite having one All-Pro (corner Stephon Gilmore) and then a bunch of good-but-not-transcendent talent at other spots, it’s worth digging deeper to try to figure out why, exactly, the Patriots were so good at a time when offensive creativity appears to be winning out.
The answer, as is often the case when you’re dealing with Belichick, is that the Patriots were both 1) well coached and 2) well coached in a specific way meant to stymie the way offenses have evolved recently. Let me try to explain.
NFL teams have the most success when they attack the middle of the field. Particularly in the intermediate area of the middle of the field. On throws between the hashes that traveled 11-to-20 yards downfield, teams added 0.74 Expected Points per attempt on average. It was the most fertile area of the field by a decent margin, according to play-by-play data from nflscrapR.
At any depth, attacking the middle of the field was the most productive strategy, an intuitive result with those throws being shorter and, in theory, easier to make than throws to the outside.
This is hardly a new finding and it won’t come as a surprise to defensive coaches, many of whom have built their defense with the idea of defending the middle of the field first and foremost. Nick Saban, who coached with Belichick in Cleveland, is one of those coaches. And the best ways to defend the middle of the field, according to Saban, is playing Cover 1.
“I think [Cover 1] is the best coverage in ball,” Saban told a group of high school coaches at a clinic way back in the early 1990s. “It’s absolutely the best coverage in ball. They can’t run the ball. The quarterback’s gotta throw the ball outside. He can’t make any of the easy throws like when you play zone.”
Cover 1, to Saban and most defensive coaches, is a man coverage with a safety in the deep middle of the field (MOF below) and a free defender (usually a linebacker or safety, called the “rat” by Saban) lurking over the middle.
If a defense is good at playing Cover 1, it’s probably going to be a good defense overall. That was certainly true for New England in 2019. According to Sports Info Solutions, the Patriots boasted the NFL’s best pass defense when playing Cover 1, allowing -0.39 EPA per attempt.
Given those results, it’s not surprising that New England led the NFL in Cover 1 usage. Most teams would love to live in man coverage but just don’t have the personnel to do it.
The Patriots do.
New England might have the deepest group of defensive backs in the league, led by perennial all-pro Stephon Gilmore, who can match-up with just about every receiver type out there. Behind him is J.C. Jackson, a big corner who can get physical with like-minded receivers. Jason McCourty is a smart veteran with good speed. Johnathan Jones has even more speed and can be used against burners like Tyreek Hill. And then there are the safeties. Devin McCourty is a centerfield ace whose cornerback experience allows him to drop into the slot when needed. Strong safety Patrick Chung is often asked to serve as an auxiliary linebacker but can also match-up with tight ends.
Having all of that talent certainly makes Bill Belichick’s job much easier. When you have an answer for just about every receiver the NFL has to offer, it’s so much easier to play man coverage. But this isn’t a one-way relationship, with the coach just riding his talent to success. Belichick’s scheme, which was developed during his time in Cleveland with Saban, makes the job of his players easier, as well. And it was a big reason why the Patriots defense have been so damn good at playing Cover 1.
Two concepts, in particular, are the secret to New England’s success playing “the best coverage in ball.” The first is a set of rules that dictates how the Patriots defenders will play when there is a safety in the deep middle, as there is in Cover 1. The second is a defensive scheme that makes throwing over the middle — where every offense wants to attack — a dicey proposition when playing the Pats.
The Divider and Position Maintenance
Those two terms — which are interconnected — don’t sound terribly exciting and might sound a bit daunting, but the concept is pretty simple. And once you learn the overarching concept and start to recognize it when watching a game, you won’t be able to unsee it.
Both the divider and position maintenance are based on where a defender’s help is located on the field. In Cover 1, it’s the middle of the field. In the deep part of the field, you have the safety positioned around 15 yards off the line. In the intermediate area, you have what’s known as the “rat” in Saban’s terminology.
If a receiver’s route takes him inside, he’s working toward the defender’s help, so it only makes sense for the defender to shade toward the outside. But the distance to that help depends on where the receiver is located, obviously. If he’s lined up out wide near the sideline, that safety or rat isn’t going to be much help even on in-breaking routes from 25 yards away.
That’s where the divider comes in.
The divider is an imaginary line on the field that essentially tells the defender whether or not he has that help to the inside. It changes based on where the ball is positioned before the snap.
That divider dictates the defender’s “position maintenance,” which is another way of saying “where the defender is in relation to the receiver.” If the receiver is INSIDE THE DIVIDER, the defender plays with OUTSIDE LEVERAGE (and in a trail position since the free safety is over the top of the receiver). And if the receiver is OUTSIDE THE DIVIDER, the defender plays with INSIDE LEVERAGE (and over the top so he doesn’t get beaten deep).
The Patriots defenders line up with divider leverage in mind, but the concept applies after the snap, as well. Hence, the term “position maintenance.” The defender must maintain the proper position throughout the snap. So if the receiver starts outside of the divider but works back to the inside, the defender must adjust his position accordingly.
And the same goes for situations where the receiver starts inside but eventually works outside.
If you watch the Patriots, their pass defenders are always positioned relative to their help, whether it’s that free safety, the rat in the middle or the sideline. Take note of the cornerback to the top of the screen in this next clip. He starts on the outside of the receiver but when the receiver breaks outside, the corner adjusts.
With help over the middle, opposing quarterbacks are encouraged to make those tougher throws to the perimeter, which are already hard enough. But with the Patriots defenders shaded to the outside, they become even harder to pull off.
This shows up in the numbers: Corner routes are a popular counter to Cover 1, and teams typically do well when throwing them, averaging 0.26 EPA per attempt. But not against the Patriots. New England led the NFL in EPA allowed (-0.88 per attempt) on those throws, per Sports Info Solutions. With defenders playing in an outside trail position, receivers are forced to run around them to get to the outside and quarterbacks have to put more air under the ball, giving the free safety more time to range over and defend (or intercept) the pass.
Making those already difficult throws even more difficult is obviously beneficial, but it’s not what made the Patriots defense as good as it was in 2019. It was their defense against the throws to the middle of the field that separated them from the pack. Earlier in this article, I told you that throws to the intermediate area of the middle of the field were the most productive. Well, the Patriots were the exception to that rule, allowing -0.06 EPA per throw. The Chiefs finished second. They allowed 0.12 EPA per throw. New England was in a league of its own, and this next concept is a major reason why.
Man match coverage
One of the most popular ways to beat man coverage is to run crossing routes, which, allow the receiver to simply run away from his defender. With those routes taking receivers into the middle of the field, or inside the divider for New England’s defenders, they have a natural leverage advantage with those defenders shading toward the outside. That’s where the “rat in the hole” comes into play.
Now most defense will play with an extra defender lurking over the middle of the field when they play Cover 1. But for the most part, that player is typically reading the quarterback’s eyes rather than looking for where receivers are running. This might be a bit reductive, but for all intents and purposes, he is a zone defender.
That is not usually the case in New England. If the offense runs one of those crossing routes that works against the leverage of his man, that rat in the hole could become a man-to-man defender. This is what Saban would refer to as a “man match” concept. In a “man match” coverage, defenses aren’t just lining up and playing man-to-man all over the field. Based on the call, the assignments can change depending on the routes the receivers run. There are a lot of different man match coverages — and different adjustments within those coverages based on formation — but we’re going to focus on one, and that’s man match Cover 1.
Man match Cover 1 includes a lot of different variations — 1 Alert, 1 Invert, 1 Cross, etc. — but the overarching concept is the same: The rat in the hole will look to “cut” any crossing routes and if he gets one, he’ll take the receiver across the field and the original man defender will replace him as the new free defender lurking in the middle. Here’s an illustration of the concept:
You can see this switch take place on the field in the clip below. The rat drives on the shallow route and the original defenders floats to the middle of the field.
Here’s another example with the safeties doing a little disguising before the snap. Duron Harmon, No. 21, is lurking in the middle of the field as if he might be the rat. But that’s a disguise. He eventually races back to become the deep safety, leaving No. 32, Devin McCourty, as the rat. That means he’s lurking in the middle of the field to cover the seam route that is passed off by Jonathan Jones (31), forcing Bengals QB Andy Dalton to opt for a long, difficult throw to the sideline that is intercepted.
Against play-action, the rat can use a “ROBOT” technique, which isn’t as cool as it sounds. It simply means “roll over and back.” I don’t know where the extra O and T come from, and I feel like “ROB” would have been a more apt name for the technique and it’s also a verb, but I digress. When using “ROBOT” technique, a player will turn his back to the quarterback and try to find a crosser. You can see Dont’a Hightower doing a pretty good ROBOT in this clip.
Things really get complicated when the offense sends two receivers on crossing routes over the middle. Here, the Steelers have one receiver running a shallow route and one running a deeper in-breaking route. The Patriots’ response is art. The rat cuts the shallow, the original shallow defender takes the deeper crossing route and the original defender on that route becomes the new rat. Three assignments change on the fly in a matter of seconds…
This doesn’t happen without smart players and great coaching.
On third-and-long, ‘1 Cross’ was Belichick’s go-to call in 2019. With the Pats being among the league leaders in man coverage usage every season, they get a lot of crossing routes in those situations. So Belichick will have a safety camp at the first down sticks and look to cut off those crossing routes. Here’s an example of 1 Cross in action…
Thanks in large part to this concept, New England was the NFL’s best third-down defense. And it was particularly effective against in-breaking routes on third-and-long, leading the league in both total EPA allowed (-13.7) and Success Rate (40%), per Sports Info Solutions.
So, to return to the question I posed at the top of the article: Why was New England’s pass defense so dominant in 2019? Well, talent had a lot to do with it. An easy schedule didn’t hurt either. But Belichick’s schemes cannot be discounted. When you combine great talent and a coach who knows how to get the most out of it, you get the NFL’s best defense.
And with the Patriots offense likely taking a sizable step back after losing Tom Brady in the offseason, the Patriots will be counting on that defense, and Belichick’s schemes, even more in 2020.
For more on man match coverage, divider rules and position maintenance, check out Kyle Cogan’s (@CoachCogan) appearance on the Make Defense Great Again Podcast, hosted by Chris Vasseur (@CoachVass). That’s where most of the information used to write this article came from.