Quarter-season stat check, part II: How Fred Warner and the 49ers defense stack up

Friday’s practice began with a welcome sight for the San Francisco 49ers. Star linebacker Fred Warner galloped across the field. It looked like he was completely unbothered by the ankle injury that had kept him out of the previous two sessions. He even hopped into the air as he crossed paths with edge rusher Nick Bosa.

Nothing could be more encouraging for the 49ers defense as it continues an incremental build back to the top-5 status that eluded it last season. The 49ers finished ranked No. 10 in expected points added (EPA), a steep decline from their No. 1 finish in 2022.

The defense is back at No. 10 to begin this 2024 season, but it’s been a rollercoaster ride so far. The 49ers ranked No. 24 following consecutive defeats to the Minnesota Vikings and Los Angeles Rams. That led coach Kyle Shanahan to challenge the unit the night before last week’s win against the New England Patriots.

“They answered the bell,” Shanahan said this week. “They came out and really answered the challenge. I was really happy with our defense.”

Will Shanahan be similarly pleased after this Sunday’s test against a better opponent in record-hot weather, which can be especially exhausting for players in pursuit on the defensive side of the ball? Arizona quarterback Kyler Murray is especially difficult to corral, so more success for the 49ers would indicate that their defense is indeed headed in the right direction.

Perhaps takeaways are a good starting point for our statistical check-in on the defensive side of the ball. (We looked at the offense in part I). Yardage isn’t all that hard to come by in the modern NFL, which features rules amenable to production on that side of the ball. So successful defenses must generate disruptive plays to throw wrenches into offensive efficiency.

With a havoc rate that ranks No. 8, the 49ers are off to a solid but unspectacular start. They’ve led the league with 42 interceptions over the past two seasons but logged only three picks over September, five off the NFL lead, so there’s room for improvement there.

Much of that will depend on how well the pass rush ties with the team’s coverage units. This falls under the responsibility of new defensive coordinator Nick Sorensen. Defeats in Weeks 2 and 3 featured obvious struggles in that department. There was significant improvement in Week 4, but the anemic New England passing offense certainly made matters easier for the 49ers.

Here are the pressure rates generated by the 49ers’ defensive linemen so far, with edge rushers listed at the top of the table and tackles at the bottom. Pressure data comes from Pro Football Focus.

Bosa and Leonard Floyd have both been productive rushing from the outside. It was Floyd’s pressure, in fact, that hurried Patriots quarterback Jacoby Brissett into the interception that Warner returned for a touchdown. Ensuring quality production beyond that will be critical. That’s why the 49ers have been so encouraged by Sam Okuayinonu’s initial action. He’ll be badly needed again this week since Yetur Gross-Matos has been ruled out with a knee injury.

Thanks primarily to Maliek Collins and Kevin Givens, the 49ers’ interior rush fared well in its first game missing Javon Hargrave. He’ll be out until at least late in the season with a partially torn triceps muscle.

Finding the pass-rushing juice to replace Hargrave will be an ongoing challenge for the 49ers. That’s why it’s so important that they at least do a reasonable job slowing opposing run games (the 49ers currently rank No. 14 in EPA against the run), as doing so can put them on a better platform to rush the quarterback.

Murray will strain the line’s rushing discipline this week with his escapability. That will also test the stickiness of the 49ers’ coverage unit, which is still searching to establish a consistent identity.

Cornerbacks are listed in the top section, linebackers are in the middle and safeties take up the bottom third of the coverage table below. Coverage data comes from PFF.

Deommodore Lenoir has made the biggest strides since last season. Through one month, he’s statistically traded places with Charvarius Ward as the 49ers’ top cornerback. In 2023, Ward allowed just 0.83 yards per cover snap to lead the way; Lenoir is at 0.82 to pace the team this time. Rookie Renardo Green’s role might cut into Isaac Yiadom’s playing time as the season progresses. He already saw more snaps than Yiadom last week.

At safety, George Odum was statistically responsible for the 97-yard touchdown to Minnesota’s Justin Jefferson in Week 2, so consider the relatively small sample size when scouring these numbers. The 49ers have since integrated two other safeties, Talanoa Hufanga and rookie Malik Mustapha, who will certainly change the look of the position moving forward. Last season, Hufanga and fellow starting safety Tashaun Gipson Sr. allowed only 0.25 and 0.31 yards per cover snap, respectively, so the 49ers will want to see more efficient coverage from the position.

The Warner factor enters the equation at linebacker and positively impacts all of the 49ers’ other defensive positions. He’s forced three fumbles — one off his career high of four last season — and intercepted two passes. Opposing quarterbacks have managed a jarringly low 17.6 passer rating into Warner’s coverage. He’s anchored the 49ers’ run defense with 14 stops ahead of the efficient line to gain.

It’s been a sensational start for the 49ers’ defensive centerpiece, one that has Bosa believing that the 49ers can eventually mold themselves into one of the league’s top defenses. The team was certainly happy to see Warner back at practice Friday and charging across the field.

“He never loses confidence in a league that is a very humbling league,” Bosa said on a podcast appearance this week. “To have the mindset that you’re going to dominate every game is pretty cool. I look up to him. He’s the leader of our defense. He’s playing this year at a level that seems like it’s hard to sustain, but if anybody can do it, it’s him. Because he just puts himself in the right position every game and every play. So I hope he continues that run and I’m happy to have him on my side.”