For decades, the NFL’s standard defensive grouping has featured a front-seven mixture of defensive linemen and linebackers, buttressed by four defensive backs patrolling the secondary. This four-defensive-back look became so common that it’s earned the designation of "base defense." And for a long time, that term made sense.
But as the sport evolves, the "base defense" is no longer the actual base defense. The standard front-seven–back-four combination has become a subpackage that springs off of the new base: the five-defensive-back look known as the nickel defense.
According to the Football Outsiders Almanac, NFL teams ran nickel on 51 percent of defensive snaps in 2015, while six-or-more-defensive-back looks accounted for another 14 percent. Teams ran their "base" defense on just 33 percent of their snaps last year, and that number — which was 48 percent just four seasons prior — is likely to continue to shrink.
As NFL offenses become increasingly spread out, schemes on both sides of the ball are adapting; it’s an ongoing chess match. Front offices and coaches must find new kinds of players to accommodate these changing styles, and the new positional requirements have long-term effects on how they build rosters, manage the salary cap, and evaluate players in the draft.
NFL offenses ran with three-or-more-wide-receiver sets on 60 percent of all offensive snaps in 2015, per Football Outsiders, which is a full 11 percentage points higher than the 2011 figure. As teams spread out with three- and four-receiver sets, it’s nearly impossible to defend against offenses with "base" personnel. Hell, it doesn’t even matter if teams are running three- and four-wide-receiver sets. These days, with skill-position players becoming more versatile — tight ends that run like receivers, running backs that can run and catch — downhill linebackers and hard-hitting "box" safeties are vulnerable on every snap, even against traditional offensive formations.
Here’s Texans defensive coordinator Romeo Crennel, back in 2012:
In other words, if you’re stiff and slow-footed in coverage, the offense is going to make you pay.
Take this play from Atlanta’s Week 17 matchup with New Orleans. The Falcons come out in the "base defense" look in response to New Orleans’ two-tight-end look. Defensive personnel is typically a reaction to offensive personnel groupings, and Sean Payton knows who he wants to pick on when he gets a "base" look against his formation. Drew Brees has an explosive pass-catching running back next to him in Travaris Cadet, so the Saints run a simple dump-off play meant to isolate Cadet in coverage against linebacker Justin Durant, who, at 30, is not as spry as he once was. The Saints’ goal is to first vacate the middle of the field by running their tight ends on clear-out routes meant to draw coverage in their direction. Then, when Durant drops into the curl/flat zone at the snap, Cadet runs into it, juking outside before cutting inside. He leaves the veteran linebacker in the dust with little trouble.
That’s just one example of how easily offenses can exploit the coverage deficiencies that traditional linebackers and box safeties present in base looks. In response, defensive coordinators have swapped out those traditional run-stuffing players for cornerbacks, safeties, and hybrid safety–linebackers that can hold their own in man and zone coverage.
"The trends in the NFL have become all about matchups," Cardinals GM Steve Keim told The Ringer’s Robert Mays. "[With] the mismatches you can create with certain players, [it’s important to have] players at every level of the field with versatility."
As Keim explained, those versatile players prevent your defense from getting exploited in isolation mismatches. Having the 220-pound Deone "don’t call me a linebacker" Bucannon playing at the middle linebacker spot means that when teams try to do something like the Saints did above, Bucannon can run stride for stride with even the most athletic backs.
Thanks to Bucannon’s ability to function as a linebacker, the Cardinals ran 90 percent of their defensive plays in 2015 with five or more defensive backs. Keim, coach Bruce Arians, and defensive coordinator James Bettcher have a crazy amount of versatility with players like Bucannon and safety–cornerback hybrid Tyrann Mathieu. No matter the personnel grouping, these two guys can be relied upon whether the scheme calls for them to match up against receivers, tight ends, or running backs.
In a third-and-2 against the Packers in Week 16, the Cardinals have to both respect the run and expect the pass. Bucannon is perfect for such a situation because he can thump with the best linebackers, but he’s also very strong in coverage. He lines up man-to-man with tight end Richard Rodgers when Green Bay spreads out along the line. At the snap, he jams Rodgers then trails him, breaking up the pass at the first-down marker.
A few weeks later, in the Cardinals’ divisional-round win over the Packers, Bucannon first dropped back into coverage before picking up a dump-off to fullback John Kuhn. You can see his physicality here and why Arizona loves him as a run defender.
Against the Vikings in Week 14, Bucannon drops into a middle-zone coverage, picks up slot receiver Jarius Wright when he comes across the field on a drag route, and closes on him once he’s made the catch. Bucannon takes it one step further when he has the skill to punch the ball out, and he also has the luck to have the ball land right in his lap.
Wright ran a 4.42 at the combine, and that’s the issue defensive coordinators often have in 2016: Someone has to defend those speedy slot receivers. Most of the time, pushing a linebacker outside or a safety down to defend someone like Randall Cobb, Larry Fitzgerald, or Doug Baldwin becomes a big win for the offense. To stop these dangerous "third" receivers, teams have replaced middle linebackers (or even defensive linemen) with versatile coverage players. They come in all shapes and sizes: Whether it’s Denver’s Chris Harris, Indianapolis’s Patrick Robinson, Los Angeles’s Mark Barron, or Mathieu, these players need to have an explosive first step to run in coverage against the quickest players on the field, ball skills to make plays on passes against bigger receivers, and physicality in the run game. If they can’t tackle, teams will run at them. If they can’t cover, they’ll throw at them.
As Robert Mays wrote about this week, the hulking, neck-roll-wearing, 250-pound, run-stopping middle linebacker prototype of the ’90s has slowly gone extinct because it’s extremely rare to find players in that mold with enough speed to cover. The Bill Romanowskis, Junior Seaus, Zach Thomases, and Chris Spielmans of that era wouldn’t stand a chance against the slot receivers and elite tight ends of the modern game.
For front offices, the question then becomes: How do you define these hybrid players? Are they safeties? Linebackers? Corners? Mathieu — who played slot corner about 60 percent of the time last year — just signed a long-term contract extension with an average annual value of $12.5 million, which is somewhere right between the top safety deals and the top cornerback contracts. The Honey Badger’s injury history — which includes multiple torn ACLs — might’ve gotten the Cardinals a discount, but what will happen if slot corners or hybrid safeties start getting paid like top outside guys?
It certainly would change the way that teams assemble their rosters under the cap. Now, instead of needing two starting cornerbacks, you generally need at least three, and the good players at the hybrid-slot position are getting paid a lot more than the players they’re replacing on the field. (Corners make several million more per year, on average, than middle linebackers.) In fact, considering all the things their versatility allows a defense to do, these hybrid players might even become more valuable than their outside counterparts, and demand always dictates price. There’s an evolution happening on the field, and it could be coming for the salary cap, too.
With money constraints in mind, teams now have to make sure to find and develop slot players early. The current salary cap remains a zero-sum game, and if you’re paying two or three cornerbacks top dollar on their second contracts, you’re going to be limited elsewhere on the roster.
This, in turn, changes the way that teams approach the draft. As Milwaukee Journal Sentinel columnist Bob McGinn wrote recently, "Personnel people talked so freely this spring about finding a ‘Bucannon’ player [in the draft], it’s almost as if it were a new position."
The good news is that colleges are running these nickel and dime defenses, too.
Seahawks coach Pete Carroll echoed this in April: "Yeah, the defenses [at the college level] are much more oriented to guys that can run. … You need more speed on the field because the ball is thrown on the perimeter so much, guys have to chase and pursue."
It creates a challenge for evaluation because while the pro game is slowly spreading out, it’s currently not as wide open as the college game. Teams still have to measure speed, but must also consider tackling ability, which doesn’t get tested as much at the Division I level. NFL franchises have to strike a balance between getting smaller on defense while continuing to stop the run.
The three- and four-receiver sets aren’t going anywhere, and defensive coordinators will continue to favor personnel groupings that allow them to best defend the pass while remaining competent against the run. This conflict calls for quality coverage players at the nickelback–slot corner and hybrid-safety positions. Soon enough, maybe these tweeners will become their own positions.
Going even further, there’s an idealistic timeline in which dime looks could supplant the nickel as the NFL’s base defense. Fat guys get completely phased out of the game of football. Everyone on the field ends up being 6-foot-2 and 220 pounds and everyone will run 4.4 40 times with 38-inch verticals. Positions will no longer be necessary, and everyone will operate A-11 offenses.
Of course, we might just see more teams make like the Titans and adopt "smashmouth" looks to exploit shrinking NFL players. There’s always a reaction.
The future remains a mystery, but right now: If you’re a defender that plays anywhere off the line of scrimmage, you better be able to cover.