SANTA CLARA >> It’s not that Brandon Staley wanted to stop being a head coach. That decision was made for him when he was fired by the Los Angeles Chargers after 48 games and a 24-24 record.

The onslaught of second-guessing in terms of strategy, tactics and personnel has ceased after joining the 49ers as Kyle Shanahan’s assistant head coach. At 41, Staley is young enough and bright enough to be a head coach again, but he’s enjoying a career reset and reintroducing himself to his favorite part of the profession.

“Before I became a head coach I was coaching players and I think that’s what all of us enjoy the most,” Staley said recently. “I think that’s what Kyle enjoys the most is coaching players. To have that direct impact on the guys, that’s always going to be the best part of the job. And to be able to work with a new group of players, have an impact on a new group of people, that’s energizing for me.”

Staley, fired by the Chargers with three games remaining and a 5-9 record after a 63-20 loss to the Raiders, is known for a defensive acumen such that it was a foregone conclusion he’d land another job. Rather than resurface as a defensive coordinator — as he was under Sean McVay for the Rams in 2020 — Staley took a more wide-ranging position with Shanahan and the 49ers.

Nick Sorensen was elevated from a defensive passing game coach to coordinator, and Staley came to lend his eyes, ears and insight in all areas of the defense. Sorensen will call the plays in accordance with Shanahan’s beliefs on defensive strategy. Staley will be the football equivalent of a baseball bench coach, mostly silent in a media sense but a trusted consultant for both players and coaches alike.

“Head coaching is so global and your attention is divided,” Staley said. “You’re trying to affect all aspects of the team. I get to do that at times, but more my focus is trying to teach players from the ground out from a fundamental standpoint.

“That’s fun for me, to work on their game, get on the grass, be in the film room, get to these guys and give some new perspective. And I’m learning a lot too.”

Sorensen has been immersed in the 49ers’ defensive system since 2022 and worked on the inside with Shanahan while predecessor Steve Wilks did not. He’ll be the defensive play-caller and welcome Staley’s input without looking over his shoulder. Staley will be a sounding board if necessary, at practice and up in the booth on game days while Sorensen coordinates on the field.

That’s the plan, anyway.

“It’s been great having him here,” Sorensen said. “He’s got a lot of experience and it’s huge. It’s been awesome.”

Staley’s presence has already been felt in terms of defensive scheme. The 49ers have been with an attacking four-man front with taking a step back being a foreign concept since 2017.

Staley ran a 3-4 defense with the Rams in 2020, and his Chargers teams did as well. One of his outside linebackers with the Rams was Leonard Floyd, who signed with the 49ers as a defensive end. He used Khalil Mack as a pressuring outside backer as well.

Defensive end Nick Bosa likes what he sees so far, even if it means dropping into coverage on occasion.

“In the NFL you have to evolve every year and we’ve had a lot of success at what we do and teams are starting to game plan it and have answers for us,” Bosa said. “We have a lot of athletic defensive ends. I don’t mind dropping. It’s kind of fun. Not something I do often but it keeps ’em honest and it could end up getting me more sacks by them not knowing exactly what we’re doing.”

Staley has assumed some of the work with the defense that Sorensen had previously on the back end and has quickly bonded with players. Isaac Yiadom said he and Staley became close in Denver in 2019 even though he was a cornerback and Staley was coaching outside linebackers.

Cornerback Deommodore Lenoir calls Staley a “genius” and dubbed him “the defensive Shanahan” in a radio interview.

“He’s a charmer,” Staley said.

Both cornerbacks cited Staley’s education on playing the percentages and being aware of tendencies. Why worry about a first-down fade pattern if the opposition has barely thrown it all year? The idea is to get the players thinking on their feet, playing fast and getting to the ball.

“Any player, particularly young players, they come into the NFL and there’s just so much to learn on your own side of the ball — new techniques, new schemes, new roles,” Staley said. “What they’re defending is different than anything they saw in college. What you’re trying to do is simplify the game for them. Instead of thinking of everything, it’s ‘These are the things that are going to impact you playing well.’ You’re trying to eliminate things they’re thinking about, not increase them.”

PRACTICE NOTES >>

Brandon Aiyuk, for the second straight day, observed practice down the sideline mostly alone, although he had quick chats with injured cornerback Yiadom (ankle) and wide receiver Deebo Samuel during the two-hour session. … Tracy Walker III and Darrell Luter Jr. intercepted fourth-string quarterback Tanner Mordecai, and Chase Lucas picked off Josh Dobbs. … Ricky Pearsall suited up for offensive warmups in his first action since aggravating a shoulder injury Aug. 6. ... George Kittle caught a 50-yard touchdown pass from Brock Purdy against the coverage of Renardo Green and George Odum. … Rookie wide receiver Jacob Cowing is faring well as a returner and he had three receptions. … Overlooked in the tight end battle but quietly emerging is Jake Tonges, whose fourth catch Thursday saw him shake off Chase Lucas’ hit. … Guard Aaron Banks appeared to tweak his knee in a pileup but didn’t miss a snap. ... Jaylon Moore, Trent Williams’ fill-in at left tackle, fared well twice against Bosa in one-on-one action. An illness kept Moore from playing Saturday night. ... Fullback Kyle Juszczyk said of Williams’ 3-week holdout: “I’m confident he’ll be here soon and they’ll get things figured out.” ... Linebacker Fred Warner, showing no signs of last week’s foot issues, opened up one-on-one drills by diving to break up a pass intended for Juszczyk.

-- Cam Inman