SANTA CLARA, Calif. — When Robert Saleh returned as San Francisco 49ers defensive coordinator in January, he didn’t make significant changes to his coaching staff.

That didn’t stop Saleh from making one major addition with whom he has a long history. After the coaching cycle had done most of its spinning, Saleh and coach Kyle Shanahan hired Gus Bradley, the longtime defensive coordinator, former Jacksonville Jaguars head coach and Saleh mentor, as the team’s assistant head coach/defense.

“I’ve been with Gus for a long time and just [have] so much respect for him,” Saleh said. “While our philosophies are the same, I should say we look at it differently, if that makes sense. And it’s kind of a good yin and yang. He sees my blind spots and I can see his. … But just the overall trust and working relationship that he and I have and just overall philosophy, I think he’s as trustworthy as it gets.”

In some ways, it’s always been a matter of time for Bradley to end up in San Francisco. When Shanahan took over as head coach in 2017, he wanted to find someone well-versed in the 4-3, Cover 3-heavy defense that Bradley had helped build with the Seattle Seahawks in the early 2010s.

Shanahan thought highly enough of Bradley that he was firmly in the mix to be Shanahan’s first defensive coordinator in San Francisco, but Bradley opted to take on that role with the Los Angeles Chargers instead.

It was no coincidence that Shanahan’s ultimate hire was a young assistant named Saleh, who had spent two years (2011-2012) as Bradley’s defensive quality control coach in Seattle and three more (2014-2016) as his linebackers coach in Jacksonville.

In the ensuing years, Saleh and Bradley remained close as the coaches went through some of the familiar ups and downs that go with the profession. From 2017 to 2024, Bradley held the defensive coordinator title with the Chargers, Las Vegas Raiders and, for the past three years, the Indianapolis Colts.

Saleh, meanwhile, helped the Niners build one of the league’s most dominant defenses before leaving in 2021 to become the head coach of the New York Jets. Like Bradley, he struggled in his first crack at the top job, going 20-36 before he was fired in October.

Through it all, Saleh and Bradley stayed in touch, regularly checking in with each other even after the Jets let Saleh go. When Bradley and the Colts parted ways, it became something of a no-brainer for Saleh and Bradley to reunite in San Francisco.

“It was never about, ‘Hey, let’s get together and let’s do this,'” Bradley said. “It really just evolved. He just told me, ‘Hey, this situation came up, what’s your thoughts on this?’ And then it just kind of took off from there.”

Unlike last season, when the Niners promoted Nick Sorensen to defensive coordinator and then brought in Brandon Staley in hopes his experience would help Sorensen in his first time calling a defense, Bradley and Saleh have a strong foundation to work from.

Their two years together in Seattle were the most productive of Bradley’s career as either a coordinator or head coach. In 2011, Bradley’s defense finished seventh in the NFL in points per game allowed and ninth in yards allowed per game. That group was even better in 2012, when it was first in scoring defense and fourth in yards allowed.

Bradley has also overseen four other defenses that have finished in the top 10 in at least one of those categories. As one of the founding fathers of Shanahan’s preferred defensive scheme, Bradley brings his vast experience and knowledge of the system to San Francisco.

“Gus, I have as much respect for as any coach I’ve been around, going against him a ton, how good he has been,” Shanahan said. “I just feel very fortunate to get him here. Saleh’s been with him for a long time. They have different personalities, but they’re from very similar backgrounds, so I think it’s really cool for Saleh to have him to bounce ideas off of and kind of to challenge him in certain ways. … I think he’s been one of our huge additions this offseason.”

Bradley’s arrival comes at a critical time for the 49ers’ defense. San Francisco is coming off its worst defensive season in years. In 2024, the Niners gave up 25.6 points per game (29th in the NFL), had a defensive EPA of minus-57.71 (26th) and forced just 17 turnovers (tied for 20th). Over the final three games, they allowed an average of 38.7 points and 404.3 yards without a takeaway.

That drop-off, combined with Saleh’s availability, left Shanahan little choice but to fire his defensive coordinator for a second consecutive offseason after relieving Steve Wilks of his job following the 2023 season. The hope now is that Saleh and Bradley can not only help a defense that could include as many as six rookie or second-year starters get back to previous levels of dominance but also provide some much-needed stability.

For Bradley, 2025 will be the first year since 2008 where he doesn’t have either the defensive coordinator or head coaching title. With the Niners, his role is equal parts vague and all-encompassing.

Through the first few months of his new job, Bradley spent most of his time studying potential draft prospects and getting up to speed with what Saleh wants the defensive scheme to look like. In that time, Bradley says, his only “agenda” has been to closely observe how Shanahan and the Niners operate up close.

More than anything, though, Bradley’s top objective is the same as it will be this season: to serve as Saleh’s de facto consigliere and help him continue to evolve the defensive scheme the pair built in Seattle all those years ago.

“I want our players to play more reactionary,” Saleh said. “Where he grew up in a system where every single technique has a word, every movement has a word. He can see blind spots where I’m liberal to the point where he goes, ‘Well, shoot, we need to [do this]’ and then vice versa. So, it’s a good working dynamic in that regard.”

And if Saleh and Bradley have immediate success rebuilding the Niners’ defense? It’s entirely possible that Saleh could be on short lists for another head coaching job as soon as next year. The natural assumption is that Bradley could use this season to acclimate to the organization and be ready to step in should Saleh depart.

But Bradley knows as well as anyone that looking too far into the future is a dangerous proposition in the ever-changing world of an NFL coach.

“I’ve just lived my life saying, it’s my job to be the best I can at this position and give everything I can to this organization and this team, and then do it again tomorrow,” Bradley said. “And usually things work out.”