Richard Sherman still in a walking boot with strained calf

SANTA CLARA, Calif. (AP) — San Francisco 49ers cornerback Richard Sherman remained in a walking boot Thursday.

However he was adamant that his strained left calf is not related to his other more serious leg problems of the past year.

Sherman hurt his calf in the second quarter of Sunday’s loss at Kansas City and didn’t return. Team officials said he’ll miss at least two games, though Sherman said the only certainty was that he’d be sidelined for this Sunday’s road game against the Los Angeles Chargers.

The three-time All-Pro missed the final seven games of last season after having surgery to repair a ruptured right Achilles tendon. But given that he also had surgery on his left Achilles during the offseason, Sherman was asked whether his current left leg injury might be connected to past issues.

“It just makes it an easy story for you guys. Makes it lazy reporting,” Sherman said. “But nah, it’s getting back out there and going through the trials and tribulations of a season, wear and tear of football and taking all these reps after not taking them for eight months. Your body’s gotta get used to it again.”

The 30-year-old Sherman missed a practice leading into the Chiefs game for what the team described as a “heel” issue, so he at least was on the injury radar even before Sunday.

His absence is a damaging blow for a 49ers pass defense that ranks 27th in the NFL at 287.7 yards allowed per game. The Chargers enter Sunday ranked fifth in total offense (415.3 yards per game).

Jimmie Ward, who has spent part of his career at safety, is expected to start in Sherman’s place. Second-year player Ahkello Witherspoon, who struggled two weeks ago against Detroit, likely will man the other cornerback spot.

Compounding things is that both of San Francisco’s starting safeties, Adrian Colbert and Jaquiski Tartt, are battling injuries and their status is unknown for Sunday.

But aside from health, the biggest issue for San Francisco’s defense has been poor tackling through the first three games. Defensive coordinator Robert Saleh said his unit is getting back to basics in practice, drilling on fundamentals even when the team is out of pads.

“It’s very clear when you turn on the tape that we’re actually lunging and ducking our heads at the point of attack,” Saleh said. “When you teach tackling, everything that we talk about is you’ve got to run your body through their body.

“Get a body on a body, step on their toes, wrap up, keep your feet moving, drive for five and get them to the ground.”

The biggest culprits last Sunday were inside linebackers Reuben Foster and rookie Fred Warner, who missed six and four tackles respectively. Those two are believed to be a promising young core of the 49ers defense.

But Sunday was Foster’s season debut after serving a two-game suspension. Saleh said Foster may have been knocking rust off, but the linebacker wasn’t letting himself off the hook.

“That’s uncalled for, just missing tackles like that,” Foster said. “That’s not like us as a team and that’s not like me.”