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How the 49ers Defense Went From Weak Link to One of the Scariest Units in the NFL

Two months ago, San Francisco’s defense was struggling to find its footing. Now, it’s the strength of a team that’s one win away from a Super Bowl berth. How did DeMeco Ryans turn things around? And just how big of a role has Fred Warner played in that?

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Through two weeks of the NFL playoffs, there hasn’t been a bigger winner than 49ers defensive coordinator DeMeco Ryans. If the 37-year-old, who is calling plays for the first time in his career, wasn’t seen as a popular head coaching candidate at the start of the month, he certainly is now: In back-to-back postseason wins, his unit held the Packers and Cowboys to a combined 27 points.

Ryans interviewed for the Vikings’ vacancy last week and figures to be in the mix for others, so there’s a good chance that his first year as defensive coordinator will also be his last. But that’s a somewhat surprising development considering where his defense was about two months ago.

In Week 9, the 49ers gave up 31 points to a Colt McCoy–led Cardinals team. The loss dropped the team to 3-5, and Ryans’s defense, which ranked 23rd in EPA allowed per play at the time, was getting a lot of the blame. Having replaced Robert Saleh, who parlayed his success as San Francisco’s DC into a head-coaching job with the Jets, Ryans was seen as one of the major problems—and that prompted star linebacker Fred Warner to come to his coach’s defense.

“DeMeco is doing an amazing job,” Warner told KNBR in November. “I know since he’s the head of the defense, he’s going to take a lot of the [blame] outside of the building. … On defense as players, we know that it’s on us. It’s upon us to go out and execute the game plan that he’s set forth for us.

“I’m going to take responsibility for getting guys right to right this ship.”

Now, with the 49ers just one game away from getting back to the Super Bowl—thanks largely to the defense—it’s safe to say the ship has been righted. Since that loss to Arizona, San Francisco ranks sixth in EPA allowed and has gone 9-2.

That turnaround isn’t because of a change in tactics or personnel, but rather improvement across the unit—and the developing partnership between Ryans and Warner. The middle linebacker typically calls plays for NFL defenses, so those players are naturally viewed as the quarterbacks of that side of the ball. And like the great quarterbacks around the league, Warner is at the heart of everything his unit does. That effort on the field—along with Ryans dialing up calls off it—has given this defense new life. And it’s helped put the 49ers two wins away from the franchise’s sixth Lombardi Trophy.


It’s impossible to quantify the impact that Warner “getting guys right” may have had on the 49ers’ second-half success, but his own improvement has clearly played a large role in it. The All-Pro linebacker, who was taken in the third round of the 2018 draft, admitted that the expectations created by the record-breaking five-year, $95 million contract he signed in August had affected his play early on in the season. Warner was in a “darkish place” mentally, he said, but he was eventually able to get back to where he was before signing the big deal. And the team’s defensive turnaround just happened to coincide with that.

As an inside linebacker, Warner isn’t the most valuable player on the defense—the size of his contract was questioned because of this. But he might be the most important. Like most NFL defenses, San Francisco plays a lot of Cover 3, which features three zone defenders splitting the deep part of the field into thirds, and four defenders covering zones underneath.

One of the more popular ways to attack that coverage is to overload the defender responsible for the deep middle with a “four verticals” passing concept, creating a two-on-one:

But defenses can counter the stress that puts on that deep safety by having the inside linebacker follow the no. 3 receiver if he goes deep:

Now, this looks great on paper, but it can cause trouble for the defense if the offense puts a receiver with 4.3 speed or a star tight end at that no. 3 spot. In that scenario, you’re asking a linebacker to run with that guy downfield and cover him one-on-one. That’s usually a pretty big problem. But not when you have Fred Warner.

Warner isn’t the only linebacker capable of staying with those routes, but what makes him such a valuable zone defender is his almost preternatural feel for how offenses are trying to attack the coverage. Take this snap from the 49ers’ Week 10 win over the Rams. Sean McVay dials up one of his favorite Cover 3 beaters—a play with two intermediate in-breaking routes and an underneath route meant to draw the second level of the defense closer to the line of scrimmage.

That’s supposed to confuse Warner, who has one receiver running across his line of sight and then another settling down in front of him. The Rams are hoping he takes the bait, which would leave a window for Matthew Stafford to hit that second in-breaking route. But Warner passes off the first in-breaker to his teammate, then drops into the throwing window of the second while ignoring the bait McVay set with that underneath route. That allows Warner to get a hand on the throw and prevent a nice gain for the offense.


This next play might be my favorite example of Warner’s brilliance, and it came on a snap that didn’t even count. The Cowboys are running a concept similar to the Rams example above. There are two in-breaking routes with a bait route underneath. Watch as Warner passes off the first route to his teammate before taking a quick peek at CeeDee Lamb to confirm that he’s also running an in-breaker. After getting in the way of that throw, he breaks on Dak Prescott’s checkdown option.

Now, Prescott extended the play and eventually found Lamb open, but he was able to do that only because of a hold that negated the play. And it was Warner’s presence that disrupted the Cowboys quarterback’s first three reads and forced him to hold the ball long enough for the 49ers rush to draw that flag.

Here’s yet another example of Warner’s impact. Watch as he sinks under the route of the Packers tight end before alerting fellow linebacker Dre Greenlaw that the route is headed his way. Greenlaw is able to pick up the crosser and prevent what could have been an explosive gain, while Warner hauls ass to tackle Aaron Jones after a checkdown.

Warner will get credit for a tackle 10 yards downfield on what looks like a bad play for the 49ers defense. But it could have been so much worse. Even when Warner isn’t preventing those throws himself, he’s making sure his teammates are in position to do so.

On film, it often looks like there are three no. 54s out there on the field—and I’m sure Stafford felt like there actually were after this play from Week 10. The Rams called a simple run-pass option, and Warner’s positioning dictates whether Stafford will throw a quick pass out to Cooper Kupp or hand the ball off. Warner starts inside the box, which prompts Stafford to throw the bubble screen, and here’s what happens:

The reason these run-pass options are often so effective is because they force a defender to be in two places at once—which, of course, is impossible … unless, apparently, you are Fred Warner.

I don’t know if we have the tools to properly quantify the impact Warner makes down after down. And while I can’t say for sure whether that impact is worth $19 million a year, I can confidently say that the 49ers defense wouldn’t be this good without him patrolling the middle of the field.

Ryans certainly wouldn’t be able to get away with playing as much zone coverage as he has this season. Not without a linebacker capable of covering as much ground as Warner does. And those coverages wouldn’t be nearly as effective without the 25-year-old making sure everyone is in the right spot—before and after the snap.

That’s not to take credit away from Ryans. Ryans helped hone Warner’s instincts and attention to detail while serving as San Francisco’s linebackers coach over the past three years, and he also has the other 10 players doing their best Warner impressions and operating at a high level. At times, it looks as if the entire coverage unit is sharing one mind. Watch as it works in unison to cover up every one of Prescott’s options on this play:

It’s rare to see a defense play zone coverage and stick that tightly to all of the routes. That’s the product of good coaching—and a team that has fully bought into it.

Next up for Ryans, Warner, and the rest of this Niners defense is a familiar opponent: McVay’s Rams. Outside of Kyle Shanahan, I’m not sure there’s a coach who puts more stress on a zone-heavy defense. With all of the pre-snap motion, play-action fakes, and route concepts attacking the middle of the field, the Rams offense is particularly tough on linebackers, who are generally tasked with run and pass-coverage responsibilities on every snap. Most defensive coordinators have to do everything in their power to protect their linebackers against McVay’s tricks, but Ryans can rest easy knowing he has Warner out there to solve any problems that may pop up. In turn, Warner can trust Ryans to get the other 10 players ready to follow his lead.

Warner makes Ryans’s job easier, and the 49ers defensive coordinator provides the same benefit for his star linebacker. In that way, this feels similar to a great coach-quarterback pairing. Both parties would probably be awesome on their own; but put together, they become something special.