SANTA CLARA, Calif. -- In the days after San Francisco 49ers coach Kyle Shanahan decided to part ways with defensive coordinator Steve Wilks, he didn't have a set plan for how that role would be filled.
Shanahan did, however, know two things: that defensive pass game specialist Nick Sorensen was a strong, up-and-coming in-house candidate and that he wanted to get back to the basics of the 4-3 defense featuring the wide-9 alignment upfront backed up by mostly zone coverage.
As Shanahan and the Niners went through the interview process, it became increasingly clear that Sorensen was the right choice to execute the second part of that equation. It also became evident that there was an opportunity to bring in an experienced, outside voice - former Chargers coach Brandon Staley -- capable of providing fresh ideas to help the 49ers' defense return to its previous dominance.
Hiring two coaches for high-profile defensive staff jobs wasn't predetermined. It just happened to work out that way.
"It kind of evolved naturally," Shanahan said. "I was just pumped to be able to have the chance to get Brandon. I know we looked into him for the coordinator role, but I was really wanting to stay in-house and keep it kind of with what we had done similar in the past with our scheme and being able to add Brandon and get him on board. It was huge."
Before any of that was settled, the Niners attempted to make a different type of huge move for the vacant coordinator job: luring Kansas City Chiefs defensive coordinator Steve Spagnuolo.
Spagnuolo was on an expiring contract and figured to be a hot commodity after his defense helped the Chiefs to back-to-back Super Bowl titles. Spagnuolo ultimately re-signed with the Chiefs, but not before some tense moments for Kansas City coach Andy Reid.
"We just jumped on it knowing that teams were going to be coming after him," Reid said. "I wasn't asking questions. I was just trying to get it done."
That led the Niners back to Sorensen and, eventually, the duo of Sorensen and Staley, who they believe can provide the right combination of continuity and fresh eyes. To this point, the 49ers haven't given Staley an official title, though he's expected to be assistant head coach with a focus on the defense. Sorensen is the defensive coordinator.
At the league meetings in Orlando last month, Shanahan laid out the plans for the two defensive coaches for the first time.
For Sorensen, it's simple -- he will call the defense like Wilks, DeMeco Ryans and Robert Saleh, the coordinators that preceded him in San Francisco.
"Having him in our building these last couple of years, really getting to work with DeMeco a lot of his first year and working a ton with Steve last year, really prepared him for this," Shanahan said. "He's been around the scheme; he's gone through it in these two seasons and just love where he is at from a football mind."
The hope is that Sorensen's knowledge of the scheme from spending the past two seasons with the team and from his time in Seattle --where he worked with Pete Carroll for eight seasons in a similar defense -- will help San Francisco's defense get back to its 2022 level of success. That year, the Niners were first in the league in points allowed per game (16.3), yards allowed per game (300.6) and defensive expected points added (89.58).
In 2023, the Niners still finished third in points allowed (17.5) and eighth in yards allowed per game (303.9), as well as ninth in defensive EPA (41.48). But warts were exposed, including a run defense that gave up 128.1 yards per game from Week 14 through the Super Bowl, which ranked 26th in the NFL in that span.
"I think really what we wanted to do was get back to who we are as a defense, our style of defense and Nick Sorensen had a great vision for how we could do that," general manager John Lynch said. "But you also want to consistently evolve."
That's where Staley comes in. Unlike Sorensen, Staley's background centers on a 3-4 scheme built in the mold of Vic Fangio, one of his mentors. Shanahan and the Niners are familiar with Staley's defensive work from the 2020 season, when he was the Los Angeles Rams' defensive coordinator.
Staley's Rams defense gave up the fewest points and yards in the NFL that season. The Niners got other close looks at Staley's defense when they had joint practices with the Chargers in 2021 and in a Week 10 matchup between the teams in 2022. Lynch said they came away impressed with what Staley was doing, particularly in his ability to mix and match coverages based on matchups.
"Brandon is a really intelligent guy," Lynch said. "I think Brandon gives us an ability to just continue to add layers to who we are and what we do without compromising the integrity of who we are."
In his first couple months on the job, the Niners have been able to tap into Staley's head coaching experience. Staley had been involved in personnel meetings since before free agency, offering what Lynch calls "great takes and opinions" as the team set forth to build out the roster in free agency and the upcoming draft.
When the season arrives, those responsibilities will shift to a role that seems designed to complement what Sorensen does, according to Shanahan.
"Brandon will be a big part of the game plans implementing a lot of our defense here in the off season and during the week each week preparing for teams," Shanahan said. "He will be a huge asset to our whole coaching staff."