HENDERSON, Nev. -- More than a week after their NFC Championship Game comeback victory against the Detroit Lions, the San Francisco 49ers' defense has moved on from a brutal postgame film session.

After the Niners escaped with a 34-31 win against the Lions, the defensive film review offered a few examples of how they fell behind by 17 points in the first place. The stunning reality was that, on multiple occasions, the 49ers' defense didn't have all 11 players giving maximum effort.

Last week, defensive coordinator Steve Wilks called it "unacceptable" and "embarrassing." On Tuesday, at their team hotel, a handful of Niners defenders expressed disappointment in themselves and vowed to not let it happen again in Sunday's Super Bowl LVIII against the Kansas City Chiefs.

"That's something that never needs to be coached," San Francisco safety Tashaun Gipson Sr. said. "That's something that never needs to be addressed. ... Obviously, everybody on that film can at some point on one of those plays point themselves out and said, 'Man, I could have played with better effort on that.' ... That film was hard. You had to see that and you had to hear some choice words, because that's not our brand of football. We are a lot better football team than that. It's nothing I'm worried about moving forward."

Because of those effort issues, the days after the NFC Championship Game were predictably intense. Niners defensive tackle Javon Hargrave said the entire unit "put our heads down" because it was so disappointed by what it watched and the accompanying angry words from Wilks. Coach Kyle Shanahan also called out his defense for what he considered poor backside pursuit on Detroit run plays.

The plays on the tape that drew the most disappointment both resulted in Lions touchdowns. The most evident was on Detroit running back Jahmyr Gibbs' 15-yard touchdown run in the first half. Defensive end Chase Young, whom the Niners acquired from the Washington Commanders at the trade deadline, was seen jogging toward Gibbs when the rookie running back cut back in front of him for the score.

On Tuesday, Young declined to go into detail about how that play developed, but he did acknowledge the need to never let such lapses happen again, especially with so much on the line this week.

"The only thing we're worried about is doing our job every play and preparing for this game the best we can," Young said. "We have got to do better. You're going to see it this game."

There were similar effort issues in the secondary on Lions wide receiver Jameson Williams' 42-yard touchdown run in the first quarter. According to linebacker Dre Greenlaw, the Niners deserved Wilks' ire.

"I think the most important thing is just how we felt about it as a team," Greenlaw said. "I agree to the fullest extent. I felt like we could play harder, and I felt like I could play harder too. So, you've got to look at yourself too. That's really what it boils down to."

As Gipson, Greenlaw and Shanahan pointed out, effort had never been a question for the Niners after Shanahan and general manager John Lynch arrived in 2017. But that was also part of what made the performance against the Lions so jarring. It wasn't just that it happened. It was that it happened in the biggest game of the year with so much at stake.

"For it to be on the biggest stage, obviously it's magnified a little more," Gipson said. "To be on that stage, that's unacceptable. But like I said, it's unacceptable to do it. We get paid too much money for the guys to go out there and put that type of effort on there. Myself included. So, it's just something that we just know that that's not our brand of football.

"It's just one of those things that it bit us, but fortunate for us, we were able to overcome it and be here and be in a big stage right now. "

After taking last week's pre-Super Bowl bye to reflect on the issues, optimism abounds this week that the Niners can get back to their usual level of intensity. Linebacker Fred Warner and end Nick Bosa were integral parts of the last 49ers team to play in a Super Bowl, losing to the Chiefs four years ago after blowing a 10-point fourth-quarter lead. This week, Warner and Bosa have hammered home the importance of playing at maximum capacity for all 60 minutes in order to finish the job and knock off Kansas City.

With that in mind, Hargrave said the Niners took their criticisms, absorbed them "and then we put our heads down and got back to work and back to playing Niner football."

Shanahan believes his team will return to where it has been for most of the campaign.

"Our guys take a lot of pride in what they do," Shanahan said. "They work hard every day, practice, games, since I've known them. So, I don't expect it to be any different on Sunday."