San Francisco’s recent collapse after the loss to the Cardinals was “extremely frustrating.”

Kicker Jake Moody, who suffered an ankle injury during the contest, spoiled some chances for the Niners to extend their lead with long field goals, but didn’t change the problems in the red zone. San Francisco went 1 of 6 and converted red zone chances into touchdowns on Sunday. While the absence of running back Christian McCaffrey, one of the NFL’s greatest red zone threats, hurts, it doesn’t explain all of the struggles the Niners had early in the season.

“Same thing I said last week, not very good,” Shanahan said of his club’s struggles in the red zone. “Before today started we were in the middle of the field and today we have deteriorated significantly.”

On Sunday, the Niners were tied in the second half, the first scoreless second half in a game started by Brock Purdy in his career.

A blocked field goal led to a touchdown, and a Nick Bosa interception turned into a chip-shot field goal, giving the team a 23-10 halftime lead that they couldn’t extend. Late, the Niners couldn’t slow down D James Conner, Kyler Murray and a rising Cardinals offense.

“It’s very simple. In the NFL, it costs a lot to have turnovers and not play complementary football,” Bosa said. “Since Kyle took over, this organization has found ways to win. It’s not about how good your players are, how explosive an offense is, or how good a defense is. If you turn the ball over and you can’t do that.” In crucial moments, you won’t lose on defense. It’s still early. It’s a long year, and I think we’ll respond well to it.”

With both the Niners and Seattle Seahawks (3-2) losing on Sunday, it’s a short, week-long battle for the top spot in the NFC West on Thursday night.

“I think we need to start a new chapter here,” Bosa said. “It’s pretty clear what happened and why we lost. I think it’s kind of a blessing that we’re playing this Thursday.”