How Pete Carroll’s Seahawks defense is trying to catch up with the modern NFL
May 13, 2022
The Legion of Boom defined a generation of defensive football with a play style so ubiquitous that Pete Carroll created something usually reserved for the other side of the ball: an NFL coaching tree. From 2003 to 2014, Carroll’s defense led the way to two national titles at USC, a Super Bowl with the Seahawks and years of domination at both levels marked by the most punishing collection of players in football.
That’s why, during an offseason of big changes in Seattle, Carroll’s defensive staff shakeup is a significant acknowledgement of changing winds in today’s NFL.
Carroll’s famed style of play — a base four-down linemen system, with a healthy diet of single-high coverages (Cover 3 and Cover 1) — tries to deny anything in the middle of the field and trusts the best athletes on the perimeter to win their one-on-one matchups. In Cover 1, every defender sticks to their man. And in Cover 3, which is pictured below, defenders shrink and expand in their zones as routes distribute downfield.
Football coaches like to say “coverage dictates the front.” In layman’s terms, the structure of a given coverage informs how many rushers a defense can have and what techniques the defense needs executed up front. In the NFL diagrams of single-high defense below, notice there are no notes or lines drawn for the defensive line. This means they’re able to play straight up, in what’s called one-gap defense — every player has one responsibility against the run or pass, and shrinking players’ focus enables all 11 to get to the ball or their coverage responsibility at full speed.
To thrive in this world of defense, coverage defenders need to win their individual matchups or have enough range in zone coverage to deny throws along the seams. Nearly a decade removed from the Seahawks winning a Super Bowl, it’s clear the elite talents of Richard Sherman, Bobby Wagner and Earl Thomas helped make the scheme iconic. But the framework that made it all possible comes back to Carroll, who used that defensive system to inform a unique approach to personnel management. The idea of the modern, long corner traces directly back to Carroll and general manager John Schneider, as do other height-weight-speed composite metrics used to identify the athletes needed to execute this system.
Yesterday’s successes will be today’s failures in the NFL, though. The defense that birthed and developed the Legion of Boom isn’t obsolete, but it cannot bear fruit on its own. The talent pool at wide receiver improves every year, and the spread of Carroll’s scheme led to every NFL offense developing their best Cover 3 and Cover 1 beater concepts while the Seahawks’ defensive stars began to atrophy. Seattle felt every effect firsthand: Following repeat Super Bowl appearances in 2013 and 2014, Seattle allowed eight or more yards per attempt in each of the next three seasons; more than 35% of attempted passes against the Seahawks have resulted in a first down every year since 2018; and the team’s defensive EPA per pass has fallen dramatically over that same stretch, according to TruMedia.
The NFL has been pass-first for a while, but teams responded to the Legion of Boom era with explosive-first football, looking to punish a defense as soon as the safeties roll into a single-high look. Compare any two-season sample of Seahawks football in the past seven years to 2013-2014, and you’ll find a staggering difference in the amount of 20-plus yard completions allowed. More often, teams began running receivers across the seams to stress underneath defenders, using play action to manufacture space in intermediate windows and aligning in 3×1 formations (like the right side of the diagram above) to attack mismatches in single coverage. It’s become less viable to line up every down in an “over” front (four down linemen who align to the tight end, as shown in the diagram above) and play Cover 3 and Cover 1 until the offense taps out.
Defenses have responded by reintroducing a method better suited to handle today’s game: the 3-4 defense, with more two-high safety looks. The thought leader of the NFL’s modern 3-4 scheme is former Broncos head coach Vic Fangio, whose coaching tree includes Chargers head coach Brandon Staley and Packers defensive coordinator Joe Barry. Fangio uses the odd front to stop the run on the interior and outside linebackers to control the edge while inside linebackers work in tandem with safeties to handle any potential play action throws or dropback passes. Even in the nickel/sub packages, Fangio’s defense keeps its edge defenders aligned outside of the tackle and its safeties deep. By aligning this way, his defense stays true to its commitment to controlling the edges with outside linebackers, instead of rolling a safety down in run support.
Compare the pictures below, from Fangio’s time as defensive coordinator in Chicago, to the images we’ve covered earlier. The still images alone reflect a clear philosophical difference between Fangio and Carroll.
Coaches who use a 3-4 scheme tell me the interplay between interior and edge defenders, as well as the linebackers and safeties at the second and third level, ties to a philosophy of having multiple layers within the defense. Those layers create multiplicity, and that multiplicity complicates the picture for offenses. These defenses can deny explosive passes by playing quarters coverage (a four deep, three under zone concept) or roll a safety into the box to stop the run by playing Cover 3.
Using Fangio’s time in Chicago as a reference again, the image below is a pre-snap look against a 3×1 formation, with Chicago using its nickel/sub personnel. From here, the Bears can run Cover 3 with a “buzz” rotation, meaning Adrian Amos (at the top right of the image below) would roll down to fit the run and carry the tight end vertically on passes. The Bears could also call quarter-quarter-half concept in which Amos would drop over the top of the single wide receiver to the quarterback’s left.
There are a host of other man and zone coverage options available here as well, which makes this defense particularly well equipped to handle this era of offense, by using the slot defenders and linebacker to sink underneath intermediate routes and the safeties to play tight in coverage against vertical routes. It’s no surprise, then, that in 2017 and 2018, Chicago only allowed a combined 75 completions of 20 or more yards, fewest in the NFL during the stretch. For comparison, Seattle in 2013 and 2014 gave up 62 such completions, which was also best in the league.
Presently, Carroll’s staff adjustments reflect the change of the football zeitgeist. He’s moved on from former defensive coordinators Kris Richard and Ken Norton Jr., who both began working with him at USC. Even the coaches Carroll picked up along the way — Todd Wash, Gus Bradley, Robert Saleh and Dan Quinn — have long since branched out and built Carroll’s scheme in their respective images. What’s replaced the old mainstays in Seattle is a concession to present-day trends: in-house promotion Clint Hurtt as defensive coordinator, Sean Desai as associate head coach/defense and Karl Scott as defensive backs coach and pass game coordinator.
Hurtt and Desai share a history as Fangio disciples, and Scott worked under two of the greatest defensive minds at the collegiate level, Alabama’s Nick Saban and Baylor’s Dave Aranda. The thread that ties all of these Seahawks assistants together is the 3-4 defensive structure and playing a healthy amount of split-safety coverages. As the only member of the defensive staff with experience calling the scheme, it would make sense for Desai to walk Hurtt and others through the intricacies and terminology of Fangio’s defense and packages. Scott, who has experience running a quarters coverage system, will apply the language he’s used during the past half decade between the pros and Alabama. Hurtt will be the man holding the laminated sheets and relaying calls to the field. Carroll will presumably still make the final call on what goes into the game plan.
As for player personnel changes, Seattle hasn’t quite embraced odd front world. Between Al Woods, Quinton Jefferson and Poona Ford, there’s enough size to institute a version of the base odd front in Seattle, but the Seahawks fall short on the edges. Uchenna Nwosu did a decent enough job in Brandon Staley’s defense last season, but he’s not the greatest run defender or pass rusher. And second-round pick Boye Mafe is a legitimate liability against the run at the NFL level. The cornerback room lacks a legitimate lockdown type of player, which diminishes the threat of man coverage, but there’s enough there to get by for a season, and more split-safety defense means more protection from explosive plays.
The system might serve Seattle’s personnel best is at safety. Quandre Diggs fits into every scheme, and Jamal Adams became a top-10 pick because of his play in a split-safety system at LSU. Adams is still shaky in coverage, so Hurtt will have to be mindful of how Adams is deployed no matter the defensive concept, but the multiple nature of more split-safety coverage principles makes that possible.
For a head coach in his 70s who’s spent more than a decade in his current role, it’s uncommon to fill a staff without at least one member who has several years of play calling experience. Carroll skeptics might view this as Carroll surrounding himself with potential yes men, but I take Norton Jr.’s dismissal as a sign Carroll is serious about trying something different in 2022. Given the personnel doesn’t perfectly marry the scheme, though, I’d expect a half measure of change in Seattle this season.
The Seahawks might increase their split-safety coverage usage from 2021 — which already featured a major uptick from years prior — but they could still deploy a lot of four-down fronts akin to Fangio’s nickel/sub packages. This lays the groundwork for more defensive pivoting in the future, once the unit gets better play on the edge and at corner.
After all of Carroll’s accomplishments, it would be a cruel (but predictable) ending to his career to retire after watching his brand of football be ushered out for next hot trend. If Carroll completes this rebrand and brings Seattle back to contention after many changes, the philosophical shift would shine bright as a career capstone.