In the 49ers' loss to the Chargers last week, the San Francisco secondary had some problems. Quarterback Philip Rivers threw for three touchdowns, and wide receivers Keenan Allen and Tyrell Williams combined for 10 receptions and 111 yards.
Through four games, San Francisco’s pass defense has been shaky. The team has allowed 11 touchdowns passing, tied for third most in the NFL.
Now the 1-3 Niners will try to patch some of those holes this Sunday when they play host to the 0-4 Arizona Cardinals and rookie quarterback Josh Rosen of UCLA, a talented, strong-armed passer who was up-and-down in his first start last week, a 20-17 loss to the Seahawks in which he completed 15-of-27 throws for 180 yards and a touchdown. Those stats didn’t really show how good he looked, however, because his receivers dropped several catchable balls.
Niners head coach Kyle Shanahan says Rosen is talented.
“It was impressive,” he told reporters of Rosen’s debut. “Similar to college. He’s a very good thrower. He made some very good throws in that game. They definitely, I believe, should have won that game. They had two big ones that were dropped. I think two touchdowns. It was impressive. So, as similar to college, we know we’re going against a good player. He definitely helps them.”
The 49ers secondary will likely again be without No. 1 cornerback Richard Sherman, who’s trying to recover from a calf injury. Sherman returned to practice Thursday, but Shanahan said it would be a surprise to have him back against the Cardinals. The one piece of good news is that strong safety Jaquiski Tartt is expected to play after missing the past two games. Free safety Adrian Colbert remains a question mark.
Without Sherman at cornerback, however, that position is fluid. It’s likely that Jimmie Ward, Ahkello Witherspoon and Greg Mabin will rotate at the two outside corner spots, with the coaching staff deciding before and during the game who gets the most playing time depending on performance.
“(I’m) really looking for one of them to grab hold of it and have a stranglehold on it and not let it go,” defensive coordinator Robert Saleh told the Sacramento Bee’s Chris Biderman. “When you get your opportunities in this league, never leave doubt. That’s all the way across the board. … It’s a challenge to the entire defense to grab your job by the neck and choke it out.”
Of the four outside corners, only Sherman (one catch allowed in six targets this season) and Mabin have played consistently well. Ward and Witherspoon, of whom much was expected in 2018, have combined to allow 24 catches on 38 targets.
Mabin, meanwhile, stepped in last week, allowed just two catches and had four tackles and a forced fumble. The former Iowa teammate of C.J. Beathard and George Kittle could start Sunday based on how he’s performed in practice and against the Chargers.
“He brought energy, intensity. We were happy about it,” Sherman told Biderman.
The 49ers-Cardinals game Sunday is set for kickoff at 1:25 p.m. at Levi’s Stadium. Oddsmakers have made the 49ers 3½- to 4-point favorites.