CHARLOTTE, N.C. – The boos came in the fourth quarter on Sunday when Carolina Panthers quarterback Baker Mayfield had his fifth pass batted down at the line of scrimmage, bringing his NFL lead in that category to 11.

Mayfield heard them.

Did they tick him off?

“Did we go down and score a touchdown after they started booing?’’ Mayfield said after Sunday’s 26-16 loss to the Arizona Cardinals. “Yes.’’

Carolina coach Matt Rhule heard the boos, too, but he didn’t replace the first pick of the 2018 draft in the midst of his fourth straight subpar performance during his 1-3 start with the franchise.

He also was noncommittal after Carolina lost for the 10th time in 11 games, dating back to last season, on whether he would consider a change at quarterback for the upcoming game against the San Francisco 49ers (4:05 p.m. ET, CBS) with 2021 starter Sam Darnold eligible to come off injured reserve and return from his left ankle injury and PJ Walker the only healthy backup.

Darnold may not even be an option. He told ESPN.com on Sunday that the Panthers “we aren’t sure’’ if the high ankle sprain he suffered in late August is healed enough to put him back on the field. And a league source told ESPN’s Adam Schefter on Monday “it’s going to be a while.’’

“We have to get it corrected,’’ Rhule said of the offense that has generated only 64 points and seven touchdowns in four games. “But in terms of any one person or anything like that, I just don’t think it’s right to speak on it now.’’

The time is growing near, though. The defense has played well enough to win every game. It scored a touchdown on Sunday for the second straight game, something it hadn’t done in consecutive weeks since Weeks 9 and 10 in 2005.

Sunday’s game was tied at 10-10 going into the fourth quarter, and the Cardinals led 13-10 with 11:26 to play.

Then came a batted Mayfield pass that was intercepted, setting up a 4-yard touchdown run by Arizona quarterback Kyler Murray. Then came another one on fourth-and-1 that led to a Murray touchdown pass.

Then came the boos.

“There’s no denying we have to get it fixed,’’ Rhule said of the batted passes, which have been a Mayfield issue since the 6-foot-1 quarterback entered the league.

Even when healthy, Darnold, the No. 3 overall pick in 2018, may not be the answer. Last season, when he went 4-7 as the starter, he had some of the same issues with failing to deliver under pressure that Mayfield has had this season.

But he was 3-0 as the starter earlier in the 2021 season when running back Christian McCaffrey was healthy. He had a 63.3 total QBR when McCaffrey was on the field. Mayfield's QBR is 14.7 with the do-it-all back.

At 6-foot-5, Darnold doesn’t have a problem with batted passes. As much as the Panthers struggled on third down last season (35.7% conversion rate, 35.1% when Darnold started), they didn't reach the level of mediocrity they have with Mayfield (25.5% conversion rate, last in NFL).

Perhaps Darnold's ability to manage the offense and not have passes repeatedly knocked down at the line could help.

But first the Panthers have to decide when to activate him from injured reserve and get back in game shape. That hasn’t been determined.

What has been determined is when it comes to the job he was hired to do when the Panthers traded with the Cleveland Browns to get him in July, he isn’t getting done.

“Obviously, I’m frustrated with the fact we’re 1-3,’’ Mayfield said. “That’s it, though. We’re four weeks into the year. We can sit here and let you guys pile on us, or we can come together as a locker room. That’s exactly how we’re going to handle it.’’

One thing is for sure: Mayfield hasn’t lost the locker room’s confidence.

“Baker’s our guy,’’ guard Austin Corbett said. “He’s our leader. He does a fantastic job every single week of getting us all on the same page. And he’s going to keep doing that same thing.’’

Said McCaffrey, “I know all of us, as well as myself, have full confidence in Baker and his ability to play football.’’

Mayfield hasn’t lost confidence in himself, either. He’s just not performing at a winning level, and that’s something Rhule has to address because the coach's future is also at stake.

“I don’t really care about the fact that our fans are booing,’’ Mayfield said. “We’ve got to figure it out. When we win, it’ll still be just us in the locker room. And that’s really all I care about.’’