The Vikings were the NFL’s last undefeated team when they turned the ball over four times in a 21-10 loss at Philadelphia on Oct. 23.

But no one at Winter Park was panicked. They were 5-1. What could go wrong?

The loss was an aberration, right? The offense hadn’t turned the ball over while going 5-0. The defense had four more takeaways while holding the Eagles offense to 13 points. And, besides, in eight days, the Vikings would be at Soldier Field facing a 1-6 Bears team on “Monday Night Football.’’

This was the quintessential NFL bounce-back scenario. The Vikings would drop the hammer. On the Bears, not their toes, and head home to face the Lions. Vegas agreed. The Vikings were a 5 ½-point favorite.

“You go in [to Chicago], you’re definitely expecting to win,” Vikings defensive tackle Tom Johnson said Wednesday. “After having such a great start and then losing to Philly, we were expecting to come in and make a big play and use that momentum to ride us into the season. We were expecting to turn around and pound the pavement and get back on track. But it just didn’t work.”

No, it didn’t. Bears rookie Jordan Howard had 202 yards from scrimmage and Chicago sacked Sam Bradford five times in a 20-10 win. The Vikings never would recover.

A week later, in the most unbelievable on-field moment in a season filled with unusual off-the-field moments, the Vikings fell to Detroit when players and coach Mike Zimmer essentially celebrated 23 seconds too soon.

Zimmer called for a prevent defense after a go-ahead touchdown, later saying it was his biggest regret. With no timeouts, Lions quarterback Matthew Stafford fired two bullets for 35 yards and spiked the ball. Matt Prater kicked a game-tying 58-yard field goal and Stafford won it in overtime.

“When we were 5-0, the ball was rolling our way,” cornerback Captain Munnerlyn said. “We started losing those games and it felt like it was a ripple effect. It just kept going on and on and on. There’s [23] seconds left on the clock and you’re like, ‘There’s no way they can drive the ball down there on this Vikings defense.’ They did.”

A year after going 7-3 in Weeks 7 through 15, the Vikings went 2-8 to fall to 7-8 and out of the playoff race heading into Sunday’s season finale against the Bears at U.S. Bank Stadium.

“We felt like we laid an egg [at Chicago] on ‘Monday Night Football,’ ” Munnerlyn said. “We definitely felt like we were still OK. But we couldn’t stop the bleeding.”

The Vikings finally bled out, giving up 72 points in back-to-back losses to Indianapolis and Green Bay as the playoff hopes officially went splat on Christmas Eve at Lambeau Field.

So here we are. The Vikings are the NFL’s sixth team to start 5-0 and miss the playoffs. They’re also the first team to do it twice, having started 6-0 in 2003.

“This has been the weirdest and craziest season I’ve ever been a part of,” Munnerlyn said.

He makes a good point, at least for the 48 players who weren’t Vikings in 2010. For the other five — Chad Greenway, Brian Robison, Adrian Peterson, Everson Griffen and Marcus Sherels — they’ll see Captain’s 2016 and raise him another promising season in which the team, the coach and even the stadium collapsed.

“Captain hasn’t been here long enough,” Greenway said. “We’ve had a lot of crazy things happen this year. But 2010 was by far the more bizarre year.”

This year, the Vikings lost Teddy Bridgewater to a freak knee injury during a noncontact drill 12 days before the season. In 2010, Brett Favre was coaxed back in August, but his bagful of magic was emptied seven months earlier with his final pass in the NFC title game loss at New Orleans.

This year, offensive coordinator Norv Turner resigned on Nov. 2. In 2010, head coach Brad Childress was fired on Nov. 22 — 368 days after he had received a contract extension through 2013.

This year, Zimmer had four eye surgeries and had to watch from home as special teams coordinator Mike Priefer coached the game against Dallas. In 2010, defensive coordinator Leslie Frazier coached the team’s final six games, going 3-3 after a 3-7 start.

This year, the Vikings’ team plane got stuck in the snow taxiing to the gate in Appleton, Wis. Players had to be lowered from the ark, er, plane two-by-two in a fireman’s bucket. In 2010, the Metrodome roof collapsed the night before the Giants game, forcing a Monday night “home” game at Ford Field in Detroit. The Vikings also played the NFL’s first Tuesday game since 1946 when the threat of a snowstorm delayed a game in Philadelphia by two days.

This year, Adrian Peterson and both starting offensive tackles joined Bridgewater on injured reserve before the bye week. Mentally-spent kicker Blair Walsh was mercifully released. And by the time Peterson returned for 12 more ineffective snaps in the Week 15 loss to the Colts, the Vikings were using their seventh combination of starters on the offensive line.

Of course, the 2010 season started with Pro Bowl receiver Sidney Rice needing hip surgery from an injury suffered in the NFC title game. Percy Harvin would miss two games because of migraines, and, of course, the SuperFreak himself, Randy Moss, would provide his own batch of bizarreness when he arrived in October from New England for a third-round draft pick.

Moss’ second stint ended less than a month later. After a loss at New England, Moss ripped Childress and teammates in a strange postgame interview in which he asked and answered his own questions. Childress cut him the next morning and was fired himself two weeks later.

“It would be hard to find more that went wrong in a season than 2010 and 2016,” Greenway said. “This year, the biggest thing is the frustration of not being able to put a finger on what’s gone wrong.”

Greenway doesn’t use injuries as an excuse because every team experiences injuries.

“I’ve thought about it a lot and there’s no one specific thing to explain what exactly changed after the bye,” he said. “We go into the bye 5-0 and come out and can’t figure out a way to win a game. It’s been strange and unfortunate. But here we are.”