49ers’ defense has underachieved so far under coordinator Sorensen

SANTA CLARA — Nick Sorensen is on the hot seat although not in his own building.

The third 49ers’ defensive coordinator in three years is a topic of conversation on the radio waves as well as social media, and not in a good way as his unit has struggled with the rest of the team during a 2-3 start.

It’s not exactly new ground where the 49ers are concerned. There were segments of the fan base that wanted to run Robert Saleh out of town before his unit evolved into one of the NFL’s best in 2019 en route to the NFC championship. When the 49ers started 3-5 in 2021, DeMeco Ryans was getting his share of criticism.

As for one-and-done Steve Wilks, he had to be ordered from the press box to the field by coach Kyle Shanahan in-season and as an outsider never seemed to be a match with the 49ers.

Sorensen, having been with the 49ers since 2022, was supposed to represent a return to the Saleh-Ryans days. Instead, the 49ers are coming off a 24-23 loss to Arizona in which they blew a 23-10 halftime lead.

The 49ers defense, which has already lost defensive tackle Javon Hargrave for the season (torn triceps), will be without 2022 All-Pro safety Talanoa Hufanga for the next month or so with torn ligaments in his wrist.

Five games into the season, a 49ers defense that hoped to go from good to great has been mediocre. They’re 10th in defensive yardage (307.8), 13th against the pass and 10th against the run. They’re giving up 4.7 yards per carry, ranked No. 21 and are 12th in points against. They have eight takeaways in five games, contributing to a turnover margin of zero.

The 49ers defensive backfield doesn’t have an interception after having 16 of a league-high 22 picks a year ago.

But on the day Saleh was fired as head coach of the New York Jets and was immediately being trumpeted as an immediate replacement for Sorensen by an impatient fan base, coach Kyle Shanahan’s evaluation was more kind than brutal.

“I think Nick’s done a real good job,” Shanahan said. “I’ve been impressed with him since the beginning. Each week, I like how he handles the defensive staff, how they set up the practices. I like the game plan. I like how he’s called it.”

Sorensen was an in-house hire after Shanahan reportedly made overtures to hire the Jets Jeff Ulbrich (New York denied permission) and told Bill Belichick he could join in any capacity he wanted.

Through five games, Sorensen said Tuesday his dilemma is between second-guessing himself and staying true to the principles he believes in when it comes to defensive football.

“You don’t ever have regrets, but there’s always things you want to improve on,” Sorensen said as the 49ers  prepared to visit the Seattle Seahawks (3-2) Thursday night. He fluctuates between wondering if he could make dramatic change or instead simply coach the existing system better.

“You don’t want to get too far off the fundamentals of your beliefs,” Sorensen said. “That’s what I lean into more than anything, and then that’s how we get better fundamentally, with coaching and how we play and how we practice. You have to trust your process.”

Having led the 49ers’ weekly “ball” meeting last season that stressed taking the ball away, Sorensen is chagrined that his defensive backfield has yet to record an interception. Defensive assistant Brandon Staley now runs that meeting with Sorensen having ascended to coordinator.

The four 49ers interceptions have come from linebacker Fred Warner (two), linebacker Demetrius Flannigan-Fowles and Nick Bosa.

“We’ve got to attack it more,” Sorensen said. “It’s one of those things with the mindset of, `When (the ball) is up, it’s ours.’ Be the aggressor. Just hasn’t happened yet. We’ve got to be more aggressive.”

Among the topics addressed by Sorensen was a 50-yard touchdown run by Arizona quarterback Kyler Murray — “We didn’t bump out and got caught up” — and too many missed tackles.

“We coach our guys to take their shots,” Sorensen said. “If we’ve got two guys coming, that’s not a bad missed tackle.”