Late in Week 13 of the 2018 NFL regular season, a seed was planted for the next step of pass defense in the modern NFL. Despite a 30-17 loss, the Detroit Lions held the Los Angeles Rams to just 195 passing yards. It was an impressive feat for a defense that finished the 2018 season ranked 31st in DVOA against the pass facing one of the league’s best and most explosive offenses.
Detroit’s plan deployed Cover 4 — or Quarters — in the secondary, a coverage that splits the defensive backfield evenly between four defenders. The coverage has a few benefits. The responsibilities allow defenders to play back, which eliminates the advantage of the offense creating mismatches with pre-sna[ motion — something the Rams have frequently done under Sean McVay. It’s also the easiest way to play match coverage, which sees defenders switch from zone to man as the routes progress.
After the Lions showed some success against the LA passing attack, this coverage was later adopted by future Rams opponents in the Chicago Bears and Philadelphia Eagles. The Rams were just 12th in offensive DVOA for the remainder of the regular season. The coverage had its biggest impact when used the New England Patriots in the Super Bowl, when the Rams were held to just three points.
Opponents have brought this strategy to the 2019 season to slow down the Rams. Only the Jacksonville Jaguars have seen Cover 4 run against them on more pass snaps than the Rams this season. LA has still struggled against the coverage with one touchdown, three interceptions, five sacks, and minus-0.15 Expected Points Added per attempt against Quarters in 2019.
This coverage hasn’t only been limited to attempting to stop the Rams, it’s something that has increased leaguewide.
Per Sports Info Solutions charting, there have already been more drop backs facing Cover 4 in 2019 (1,520) than there were throughout all of 2018 (1,182). But the increased usage hasn’t led to a shutdown of opposing offenses. Last season, teams averaged 7.33 yards per attempt against Cover 4 with an equal 4.0% touchdown and interception rate. This season, teams have a little more success with 7.99 yards per attempt, still a 4.0% touchdown rate, but a lower interception rate at 2.3%.
For overall coverages, Quarters still falls well below how often Cover 1 and Cover 3 are run across the league, though it has surpassed Cover 2. By production, the numbers don’t show much of an advantage over the other coverages, except for sack rate.
|Coverage||Drop Backs||Comp%||YPA||TD%||INT%||Sack%||EPA/Att||Positive Play%|
*data provided by Sports Info Solutions
In November of last season, Doug Farrar wrote a three-part series for USA Today on how defenses could and should adapt to modern NFL offenses. The main takeaway was how defenses could use more match coverage, especially out of Quarters.
While defenses are using Cover 4 more often, they haven’t exactly mastered the matching of 2019 offenses. For this to work, defenses need both the communication to pass off routes and the player capable of holding up in coverage. Through the first nearly three-quarters of 2019, defenses have either played Cover 4 as a more passive zone coverage or they have run into some communication issues that create coverage busts.
Over the first two weeks of the season, Kansas City Chiefs opponents attempted to defend the explosive passing offense with Quarters. Between the Jacksonville Jaguars and Oakland Raiders, the Chiefs saw a combined 14 pass attempts against Cover 4. Those snaps didn’t phase Patrick Mahomes, Andy Reid, or the Kansas City offense.
In Week 1, the Jaguars defended a tight look from 11 personnel (three wide receivers) by the Chiefs with Quarters. Kansas City ran two deep crossing routes to the left side of the field from the outside receiver on each side of the formation. With no other deep routes, all of Jacksonville’s deep defenders followed the crossers. However, Sammy Watkins crossed from the left and leaked out the right sideline late with no defender in his way for a 49-yard touchdown.
14 pass attempts might not sound like a lot, but none of these teams are running Cover 4 or match coverage as a base, so these coverages are game planned in for certain situations. After the Chiefs had success in these two games against the coverage, other defenses seemingly have been scared off by the coverage. Mahomes has thrown against Quarters on just eight other pass snaps since Week 2. Though it should be noted opponents tried the coverage in an attempt to stop Matt Moore, who saw 16 snaps against Cover 4 in two games against the Minnesota Vikings and Green Bay Packers.
San Francisco Secondary
No defense in the league this season has used Cover 4 more than the San Francisco 49ers, who are tied with the Carolina Panthers for most pass snaps with the coverage. If teams want to see what the best-case scenario is while using Quarters, they should look no further than San Francisco.
The 49ers have allowed a league-low 54.6% completion rate with Cover 4 and have allowed just 5.31 yards per attempt. San Francisco’s defense has also seen a boost in the pass rush with Quarters — a 13.8% sack rate and a 39.6% pressure rate, both above the already impressive overall numbers of a 11.6% sack rate and 30.4% pressure rate on all plays.
San Fransico isn’t just passively playing back in zone coverage and often their use of Cover 4 is disguised as Cover 3 before the snap. That typically asks one of the defensive backs to aggressively drop back pre-snap and asks a lot of the secondary to communicate but with the likes of Richard Sherman, Ahkello Whitherspoon, Jaquiski Tartt, and Jimmie Ward in the backfield, that has not been an issue. As is the case with many schemes, having the players who can execute it at a high level can be just as, if not more, important. San Francisco certainly has that.
Last week, the 49ers used this against Kyler Murray and the Arizona Cardinals. San Francisco initially showed an 8-man box against Arizona’s two-back backfield with a tight end in the wing, but before the snap, both Tartt, who was in the box, and Sherman to the offense’s right bailed back. The coverage held the two deep routes in front of the defenders and with pressure, Murray was forced to leave the pocket and throw a contested short pass that was broken up.
A similar play occurred the previous week against Russell Wilson and the Seattle Seahawks. On a 1st and 15 early in the second quarter, Seattle came out with a 2×2 set. Before the snap, tight end Luke Willson motioned from outside to the slot, but that didn’t impact the 49ers defense, who came out in a Cover 3 look. San Francisco dropped back into Quarters before the snap and immediate pressure forced Wilson out of the pocket. The downfield coverage held up and, like Murray, Wilson had to throw a contested short pass to a receiver coming back to the ball.
One of the appeals of Quarters coverage is that it typically shuts down deep passes and keeps the ball in front of the deep defenders. That is arguably the biggest strength of the 49ers’ version of the coverage this season. Just eight passes at least 20 yards in the air have been attempted against San Francisco when the Niners have been in Cover 4 this season and none of them have been completed. That’s a boost for a defense that has relative struggled against the deep ball this season. Per Football Outsiders, the 49ers rank first in DVOA against short passes but just 14th against deep passes.
The pre-snap disguise also makes the opposing offense hesitate just for a moment to identify the coverage, which is more than long enough for San Francisco’s pass rush to breakthrough. The pre-snap to post-snap shift was something that made the Patriots’ use of Quarters so effective in the Super Bowl against the Rams.
Back to the Future
There has clearly been a leaguewide effort to use more Cover 4 in 2019, but not enough teams have fully implemented the intricacies of the coverage — especially with the addition of matching — for it to make as much of a difference as it could. There are still a number of teams using Cover 4 as a passive zone coverage instead of the counter to modern offenses it could be. Still, having defenses at least start to phase the coverage into their game plans is a good sign that defensive minds across the league are starting to adapt and won’t get completely left behind in this era of offensive explosion.
Offenses are still a step or so ahead of defenses, but there is hope for defenses to step up and be more innovate. With younger minds coming in on the defensive side of the ball, as has recently been the case on offense, the process could be sped up more than it has been over the past seasons.
There’s still more to be done, but defenses around the league embracing, at least somewhat, a coverage that could help spark a defensive revolution is a good start.
Editor’s note: a previous version of this article featured a play from the Week 2 Raiders vs Chiefs game that might have been Quarters coverage.