SANTA CLARA, Calif. -- After coach Kyle Shanahan and general manager John Lynch's tenure with the San Francisco 49ers started with two tumultuous losing seasons, they made an important decision regarding the franchise's future identity.
For better or worse, these Niners were going to be built on the foundation of a dominant defensive line capable of wrecking games. In 2019, they used the No. 2 pick on defensive end Nick Bosa roughly six weeks after sending a second-round pick to the Kansas City Chiefs in a trade for edge rusher Dee Ford, whom they promptly signed to an $85 million contract.
The turnaround was as successful as it was dramatic, as a front four of Bosa, Ford and defensive tackles DeForest Buckner and Arik Armstead led the charge to a 13-3 record, an NFC championship and a narrow loss to the Chiefs in Super Bowl LIV.
With the exception of the injury-ravaged 2020 season, the engine that's driven these Niners to three NFC Championship Games in four years has been a defensive line that has never lacked for resources. Which is why, when that Bosa-led group manages a pressure rate of 25% and fails to sack Minnesota Vikings quarterback Kirk Cousins on any of his 44 dropbacks -- which is what happened in Monday night's loss -- it stands out above any other deficiency.
"We didn't have any sacks today and when you go against a quarterback like that, you have to make him uncomfortable," Shanahan said Monday night. "And he didn't seem too uncomfortable."
As the reigning Defensive Player of the Year, Bosa -- who missed training camp because of a contract holdout -- puts much of the onus on himself to jump-start the defensive line. In the locker room after Monday's loss, Bosa spent roughly 15 minutes chatting with All-Pro linebacker Fred Warner about how they as leaders can return the defense to the lofty standard it has set. They'll start that quest Sunday against the 3-3 Cincinnati Bengals (4:25 p.m. ET, Levi's Stadium, CBS).
"We have a lot of really good players on the D-line and there's obviously a lot invested in it and you have to make the plays when they're there," Bosa said. "I can only focus on myself and there were definitely a couple opportunities there where I could have changed the game and I need to do that with the kind of player I'm supposed to be."
That all has to start up front, where the Niners have $41.4 million in salary cap dollars devoted to the defensive line this season (fifth in the NFL) and a league-high $61.64 million dedicated to the position group for 2024.
So far, the return on significant investments in Bosa, Armstead and defensive tackle Javon Hargrave have fallen below expectations, particularly in back-to-back losses which have dropped the 49ers to 5-2. The proof is in the numbers.
The Niners have a sack rate of 4.9%, which ranks 26th in the NFL and on pace to be the lowest of the Shanahan era. For context, the 2019 team was at 8%.
San Francisco has 15 sacks, which is tied for 18th in the NFL. It's on pace for 36, which would be its third fewest since 2017.
The 49ers' pressure rate of 27.6%, which 22nd in the NFL and on pace to also be the lowest since Shanahan and Lynch arrived.
"This isn't our standard," Armstead said. "We expect to dominate games and be able to put the team on our back in situations and get off the field, so we didn't do that and we have got to get better."
Fixing the problem is far more difficult than identifying it. There are multiple factors at work. For one, they have a new defensive coordinator in Steve Wilks. Wilks arrived with two decades of NFL coaching experience, including four as a head coach or coordinator.
Wilks also walked into a place where the fiery, energetic youth of previous coordinators Robert Saleh and DeMeco Ryans had stalked the sidelines, offering chest bumps and loud screams for big plays. He also took over a defense that ranked at or near the top of most major defensive categories last year, which meant his primary task was to avoid trying to fix something that wasn't broken.
That didn't seem like it'd be a problem when the Niners landed Hargrave on a four-year, $81 million deal in March, giving Wilks even more front four firepower. Known for his propensity to blitz at previous stops, Wilks figured to do it less than he usually would with the Niners but more than they had before he arrived.
Through seven games, the Niners are sending five or more pass-rushers on 24.3% of dropbacks, their second-highest rate since 2017, trailing only the 2020 team that was forced to do it more because of injuries to Bosa and others.
"It definitely works out sometimes," Bosa said. "I'm not used to it. We're usually a rush four kind of team and it's a little different this year."
But it's also fair to point out that Wilks has, on multiple occasions this season, been forced to lean into an aggressive approach because the front four isn't getting home consistently.
When the Niners don't blitz, they have a pressure rate of 23.5%, which is 23rd in the NFL. When they do, it's 40.5%, which ranks 18th. Perhaps Wilks is feeling out the best ways to deploy his blitz packages or how to use certain players, but the fact that the Niners aren't even in the top half of the league in pressure percentage -- let alone sacks -- with and without the blitz indicates that one of their foundational pillars is showing some cracks.
To be sure, opposing offenses are game-planning ways to try to neutralize the Niners' star-studded line. The ball is often coming out quick, which explains the significant gap in the Niners' pass rush win rate (eighth-best) and their pressure rate (22nd), and teams are sending extra blockers at Hargrave, Armstead and Bosa with regularity.
After Monday's loss, Bosa said "you can kind of get lulled to sleep by some of the protections," meaning when running backs or tight ends chip and/or the offensive line slides a certain way repeatedly, you come to expect more of the same. But when they change it up, it can stop you in your tracks and lead to missed opportunities.
Of course, the Niners aren't the only defense facing offenses trying to mitigate pressure from a standard pass rush. Opposing quarterbacks are getting the ball out in an average of 2.71 seconds, which is tied with the Baltimore Ravens for 10th-quickest in the NFL.
But the Ravens are first in the NFL in sacks (29) and 10th in pressure rate (30.5%) while only blitzing 21.5% of the time. In other words, their best pass-rushers are winning consistently and, when it's time to throw a curveball, defensive coordinator Mike Macdonald is picking his spots and hitting them.
"We've got to be better and find a way," Armstead said. "Every game it's like a new offense that is trying to protect the quarterback in new ways that we have to figure out."
And soon.