The 2023 season almost started without the San Francisco 49ers’ best defensive player, Nick Bosa.
The defensive end signed a record-breaking five-year deal three days before the 49ers opened the season in Pittsburgh and, not surprisingly, he wasn’t quite himself to start the season. Bosa eventually got on track, and he was excellent in the playoffs with 28 quarterback pressures in three games, including 12 in the Super Bowl.
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But he finished with eight fewer sacks than he had the previous season and symbolized a defensive line that dipped in 2023, especially in the first half of the season. For example, the player the 49ers hoped would be Bosa’s pass-rushing bookend, Drake Jackson, had three sacks in the opener and none in the next seven games before going on injured reserve.
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The situation prompted the 49ers to make not one, but two trades at the position, first acquiring Randy Gregory and 26 days later Chase Young. Both provided moderate, midseason boosts, though the defensive end with the next-most sacks after Bosa ended up being Clelin Ferrell … with a ho-hum 3 1/2 sacks.
The 49ers also played the last five and a half games of the regular season without their veteran leader along the line, Arik Armstead. That seemed to prompt them to ask Armstead to take a significant pay cut for the upcoming season, which he rejected and which led to his release. Armstead, who had been the 49ers’ longest-tenured player, signed a three-year deal with the Jacksonville Jaguars.
That makes fullback Kyle Juszczyk, signed as a free agent in March 2017, San Francisco’s longest-tenured player and Bosa the de facto captain of the defensive line. — Matt Barrows
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By the numbers
The 49ers suffered a precipitous decline in run defense, falling from 2022’s No. 2 unit in EPA per play to No. 26 in 2023. This adversely affected the pass rush, with advantageous down-and-distance situations fewer and farther between. This problem might’ve been most evident during the disastrous first half of the NFC Championship Game when the Detroit Lions stormed out to a 17-point lead, but that was just one episode of a season-long issue.
| D-lineman | Snaps | Pass rush grade | Run defense grade |
|---|---|---|---|
1,022 | 92.3 | 76.4 | |
484 | 66.0 | 67.1 | |
471 | 60.4 | 47.4 | |
334 | 56.0 | 54.7 | |
199 | 64.1 | 38.9 | |
59 | 63.6 | 35.8 | |
54 | 51.5 | 68.6 | |
36 | 66.3 | 63.8 | |
775 | 86.5 | 51.4 | |
661 | 86.5 | 52.7 | |
544 | 71.7 | 35.6 | |
63 | 51.3 | 65.1 | |
54 | 64.4 | 37.9 | |
51 | 56.4 | 30.8 |
Grades are from Pro Football Focus
Last season’s breakdown of D-line grades suggests run defense was already a weak spot for the front in 2022 — and that it took exemplary performances from the linebackers and defensive backs to sustain a high rank that season. The 49ers lost that support from the back seven in 2023, perhaps at least partly due to schematic changes implemented by defensive coordinator Steve Wilks, who was fired after just one season with the team.
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Beyond that, the table above should make it easy to see why the 49ers felt the need to overhaul their defensive line this offseason. Too many individual performances against the run were shoddy and the absence of a consistent pass-rushing bookend for Bosa hindered the defense. It’s telling that Young racked up the second-most snaps of all the team’s defensive ends despite not arriving until the trade deadline.
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Hargrave, Armstead and Kinlaw all enjoyed good pass-rushing seasons on the inside, but all three struggled against the run. Considering the fact that Armstead had built a reputation as an anchor of a top run defense, this might come as a surprise. But perhaps it underscores the 49ers’ need for a true block-gobbling defensive tackle in the model of D.J. Jones, who left for the Denver Broncos in free agency after the 2021 season. Armstead’s run defense peaked when he’d been paired with Jones. — David Lombardi
Offseason plan
The 49ers experienced a sea change along the defensive line in March. Exiting were Armstead, Javon Kinlaw, Young, Ferrell and Gregory. In were Leonard Floyd, Maliek Collins, Jordan Elliott and Yetur Gross-Matos.
Floyd and Collins are the key additions. In Floyd, the 49ers have the first proven bookend to Bosa at defensive end since Dee Ford was a regular part of the lineup early in 2019.
Floyd has finished with at least nine sacks in each of the last four seasons and he’s appeared in every regular-season game in each of the last five. He turns 32 the day before the 49ers host the New York Jets in the season opener and likely will be the team’s oldest starting defender in Week 1.
Collins, meanwhile, is expected to take Armstead’s spot in the defensive line rotation. He’s started a lot of games, 117, over an eight-year career and last season played in a similar system for the Houston Texans. He tied a career high with five sacks, the same number Armstead had in 2023.
The team’s No. 3 defensive end is expected to be Gross-Matos, whose physique is similar to former 49ers Arden Key and Charles Omenihu and who might be able to provide the same sort of boost as a third-down interior pass rusher. Jackson, meanwhile, has not yet played to his second-round draft status and may have to hold off Robert Beal Jr., who added around 15 pounds of muscle in the offseason, for a spot on the game-day roster. — Barrows
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2023 outlook
A return to previous identity has been the 49ers’ mantra for their defense this offseason, and that effort has been rooted in a revitalization of the defensive line. The 49ers’ new collection of talent must accomplish two goals to lead this defense back into the elite realm of the NFL.
First, the 49ers must be both athletic and stout enough on the interior to dissuade opponents from running there. That’s mandatory to set up an effective pass rush, and it’s not easy coming out of a Wide-9 alignment.
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Then, the 49ers must set and maintain strong edges — especially opposite Bosa — to stymie the perimeter run and deliver an overpowering pass rush.
Do the 49ers have the pieces to accomplish their goals? Floyd is a proven, consistent veteran who should complement Bosa well. Gross-Matos projects to be the type of inside-out talent that has thrived in defensive line coach Kris Kocurek’s system.
The bigger gamble is coming on the inside, where the 49ers have replaced Armstead and Kinlaw with Collins and Elliott. But that overhaul was a bet the 49ers felt they needed to make, simply because the production and consistency there hadn’t been up to par.
They hope that 2024’s big changes enable them to reverse course. — Lombardi
(Top photo: Gregory Shamus / Getty Images)