Last year, the 49ers started out 8-0, finished 13-3, and powered their way to the Super Bowl largely thanks to their dominant defense. Only the Patriots defense had a higher overall DVOA last year than San Francisco; they also ranked second in pass defense DVOA and ninth in run defense DVOA. A lot of their success was due to the ferocious pass rush coming from their defensive line, which featured the likes of Defensive Rookie of the Year Nick Bosa alongside Arik Armstead, Dee Ford, and DeForest Buckner. Those four combined for 33 total sacks last year, terrorizing quarterbacks on a weekly basis.
This year, though, the 49ers defense has taken a step back. Bosa landed on the injured reserve in Week 2, and Ford did the same a week later. Buckner was traded away in the offseason, which has effectively left Armstead as the sole returner from last year’s dominant pass rush. Not surprisingly, he hasn’t been as effective, registering just 1.5 sacks thus far. The 49ers still rank 10th in DVOA, 13th in pass defense DVOA, and seventh in run defense DVOA, which is a testament to their defensive coordinator Robert Saleh.
That’s a big reason why Saleh will have his pick of head coaching vacancies this offseason, as the fourth-year coordinator has adapted well to his personnel shortcomings. Kerry Hyder leads the defense with 7.5 sacks, while Dion Jordan is in second place with three. It’s nothing impressive, but it’s been enough to get the job done.
Schematically, though, Saleh’s roots are something the Cowboys should be very familiar with. He spent three years as a defensive quality control coach with Pete Carroll’s Seahawks before following then-Seahawks defensive coordinator Gus Bradley to Jacksonville as the linebackers coach. When Kyle Shanahan hired Saleh as his defensive coordinator in San Francisco, it was to implement the same Legion of Boom defense that Kris Richard tried to do in Dallas the last two seasons.
Saleh very quickly established this scheme change, and the 49ers ran a Cover 3-heavy scheme with the same kind of fronts that Seattle frequently used. But heading into last season, Saleh adopted more wide fronts on his defensive line to get his talented front four some favorable matchups. It clearly worked well, but the Achilles heel of his defense is the same as it was for Dallas under Richard: fire the ball out quickly and take the short gains.
That’s the attack that many opposing offenses used last year. The 49ers surrendered a league-low 6.5 yards average depth of target (ADOT), but combined that with the tenth-fewest yards after the catch to allow the third-least first downs all year. It’s more of the same this year - an ADOT of 7.6 yards and the fourth-fewest yards after catch - which has helped this defense continue to play well despite a lot of key injuries all over.
Saleh has also adjusted his scheme by dialing up significantly more blitzes this year. The scheme he learned in Seattle and Jacksonville is notoriously shy about blitzing, and the 49ers’ 20.9% blitz rate last year was fourth from the bottom. But this year, recognizing the need to supplement his injured defensive line, Saleh has sent an extra rusher on 32% of drop backs, ranking them 13th in the NFL. It hasn’t translated to success, as San Francisco ranks 28th in pass rush win rate; however, it’s helped them avoid being completely helpless against the pass.
But for the Cowboys, this ends up being a pretty favorable matchup for them. Kellen Moore obviously is familiar with the scheme Saleh likes to use, having worked with Richard the last two years, and he’s already been running more of a quick-strike offense that’s tailored to nickel-and-dime this defense. In the last four games, Andy Dalton has had an average of 2.49 seconds to throw the ball, and in three of those games he was among the five quickest triggers in the NFL that week.
In other words, Dalton is getting the ball out quickly and efficiently. More than that, the Cowboys are averaging 86.5 yards after the catch in those four games. If they can continue that trend of quick completions that result in big gains, Dallas will be very well-equipped to succeed against this 49ers defense.