The comeback Chiefs are Super Bowl champions

The Kansas City Chiefs had struggled all night to pick up their fizzling offense, and fans who had watched their defense let them down for years looked as if they were going to rue its performance once more on the game’s biggest stage.

That’s when new coordinator Steve Spagnuolo’s defense penned a different ending to the script.

The Chiefs forced the San Francisco 49ers into a pair of punts in the fourth quarter, when they were facing a double-digit deficit for the third straight game, and that gave Patrick Mahomes and Co. a chance.

Their young star threw a touchdown pass to Travis Kelce, then another to Damien Williams, allowing Kansas City to rally for a heart-stopping 31-20 victory in the Super Bowl on Sunday night — the first championship for the long-suffering franchise in 50 years.

The 49ers still had a chance after Williams reached the ball over the pylon with 2:44 left, and a video review upheld the touchdown call that gave Kansas City the lead.

But after giving up a first down, a defense that carried a newfound sense of purpose — “swagger,” safety Tyrann Mathieu called it — made four consecutive plays when they mattered most.

Jimmy Garoppolo threw three straight incompletions, then the 49ers quarterback was sacked by Frank Clark, the $105.5 million offseason acquisition. That gave the Chiefs the ball back, Williams got loose for a clinching touchdown, and Kendall Fuller picked off a desperation pass deep downfield in the final moments to complete the standout defensive performance.

Back in Kansas City, a fanbase that hadn’t celebrated a title since the Nixon administration was finally able to exhale.

The Chiefs’ defense has been the bane of the organization for years — especially in the postseason. There was the divisional loss to the Colts in the 2003 season in which nobody punted, and the 45-44 collapse in Indianapolis in the wild-card round in the 2013 season when the Chiefs blew a 31-10 halftime lead and coach Andy Reid was once again ridiculed for his inability to win the big one.

The most heartbreaking loss, though, was the one that spurred the Chiefs to make wholesale changes last offseason.

They failed to get Tom Brady and the New England Patriots off the field in overtime in the AFC championship game, never giving Mahomes and the NFL’s best offense an opportunity with the ball.

Well, the rebuilt defense got the 49ers off the field. And Mahomes and the Chiefs did the rest, giving Reid his long-awaited Super Bowl triumph and washing away all those other postseason failures.

The defense wound up holding Garoppolo to 219 yards passing with a touchdown and two interceptions. It held one of the NFL’s best ground attacks to 141 yards rushing. And it finally quit biting on trick plays and end-arounds that caused them fits the entire first half, playing the kind of defense down the stretch that Kansas City has sought for years.

When the final seconds finally ticked off the clock, Clark ripped off his helmet and ran the length of the field, falling to his knees and staring into the sky. Mathieu pranced around in celebration, his own roller-coaster journey reaching its climax.

The defensive line that consistently put pressure on Garoppolo down the stretch looked like giddy schoolchildren as they hugged amid the flying confetti, the celebration five decades in the making finally playing out on a field in Miami.