Meanwhile, the Chiefs’ other significant offseason acquisition last year, safety Tyrann Mathieu, didn’t have a signature play in the Super Bowl but was in on six tackles. The Chiefs, after spotting the 49ers a 20-10 lead, held San Francisco to 59 yards and no points during four fourth-quarter possessions.

The pair provided the defense with the punch it needed for a much different ending than the season before, when the Chiefs lost in the AFC Championship Game. The New England Patriots scored touchdowns on their final two possessions in that game, the last one in overtime.

Many had a role in the Chiefs’ defensive turnaround this season. Kansas City had a new defensive coaching staff, led by coordinator Steve Spagnuolo, and eight players who weren’t with the 2018 Chiefs had a significant hand in the title run.

But none had an impact quite like Mathieu and Clark.

“We’ve got great leadership on this team,” safety Daniel Sorensen said. “Tyrann Mathieu, Frank Clark, those guys have led us and kept talking to us: ‘Believe in ourselves, trust in ourselves, we’re going to get better, we’re getting better.’ You see that process and we continued to get better and better and better. When it came down to it, the defense was able to make some key stops and get the offense the ball back and let them do what they do.”

The Chiefs finished the regular season seventh in scoring defense and 17th in yards allowed, both significant improvements over the 2018 season, when they finished 24th and 31st, respectively. But the Chiefs had more than statistical improvements in mind. They wanted fourth quarters like the one against the 49ers.

“There were great expectations coming into this season, but we believed that we could be in this position, especially defensively,” Mathieu said. “We knew we weren’t that far off and it was going to come down to us making plays on defense. I’m so proud of our guys on defense and our group, especially our coaching staff.

“I think our mindset was just to finish the game. I think our D-coordinator, Spags, that’s all he preaches, to never relax, to never get comfortable really until the game is over. I felt like that’s what we did.”

The Chiefs paid a premium to sign Mathieu as a free agent. They gave him a three-year contract worth $42 million, which at the time made him the NFL’s highest-paid safety.

“Tyrann Mathieu, that’s the landlord right there. He commands the field and rent was due [in the Super Bowl].”

Chiefs defensive lineman Chris Jones

But he still proved to be a good value. He was Kansas City’s top defensive playmaker, leading the Chiefs in interceptions with four and in passes defensed with 12. He also assumed immediate command of the locker room and became the team’s defensive leader.

“Tyrann Mathieu, that’s the landlord right there,” defensive lineman Chris Jones said. “He commands the field and rent was due [in the Super Bowl]. Everybody had to pay their rent and we did.

“He held everyone accountable since Day 1.”

In April the Chiefs traded with the Seattle Seahawks for Clark, who played through injuries and got off to a slow start. But he had seven sacks in his final eight regular-season games and then five sacks in three postseason games. He became just the eighth player since sacks became an official stat in 1982 to have five sacks in a single postseason.

If Mathieu was the voice of reason for the Chiefs, Clark was the one of inspiration.

“Never,” Clark said when asked if he doubted the Chiefs’ ability to rally when they were behind the 49ers by 10 points in the fourth quarter. “I don’t doubt [anything], man. We were down 24-0 against the Texans [in the divisional round of the playoffs] and in that game, I said we were going to go hit them in the mouth. And what happened? We end up hitting them in the mouth.

“This game … we were down 10 points and it’s 15 minutes to go and then [49ers players] start celebrating football like they were about to win the Super Bowl. I went out there next drive and said, ‘Y’all’s going home too, like the rest of them.'”

The Chiefs finished their season with nine straight wins. Their defense had a huge role in most of those games, starting with a Week 11 victory against the Los Angeles Chargers. Like the 49ers in the Super Bowl, the Chargers went scoreless on four possessions in the fourth quarter.

“That’s the best feeling in the world as a defense,” Clark said. “You all wonder why I feel so good about this defense? Because look at us. You put us in these crazy situations, and we don’t bend, we don’t break.”