Charlotte, N.C. – In 2016, the Vikings were inspiring visions of a Super Bowl run before they traveled to the East Coast and lost to a contender as the surgical tape holding their offensive line together fell away like molted skin.

In 2017, the Vikings were hinting they could become the first team to play a Super Bowl in their home stadium when they traveled to the East Coast and lost to a contender as their offensive linemen began toppling like shooting-gallery ducks.

The comparison is simplistic in terms of timing and personnel. The 2017 Vikings employ a different quarterback and lead running back and have remade their offensive line. Losing 31-24 to a strong Carolina team on the road is not in itself reason for concern. Finishing with 12 or 13 victories would have been considered ideal even before Sam Bradford and Dalvin Cook were injured.

But if you want to find concern in one loss over nine games, you could worry about two recent developments: Riley Reiff's injury, and a downturn in big offensive plays.

Through 12 games, the offensive line had become the Vikings' most surprising strength. By the end of Sunday's game, they had only one starting offensive lineman playing in his designated position — right guard Joe Berger. Reiff had been folded backward like a pocket knife, leaving the field on a cart because of an ankle injury. Vikings coach Mike Zimmer declined to offer more information.

If Reiff can't return soon or perform well in the playoffs, his injury could wind up being more devastating than Bradford's or Cook's. Center Pat Elflein missed the game because of a shoulder injury that is not thought to be serious, but Zimmer and the NFL in general are adept at downplaying or hiding injuries. And right tackle Mike Remmers missed another game, this time because of a back injury.

The line performed well enough for the offense to produce 24 points against a good defense, despite two dropped touchdowns, a drop by Kyle Rudolph that should have been a long gainer, and Case Keenum's worst game since October. But this team has raised expectations to the point where the line can't just be functional; it is supposed to be more engine than anchor.

Keenum had progressed from game manager to play-maker during the past five weeks, as the Vikings played the toughest stretch of their schedule. With the exception of a two-pass sequence in Washington, he had managed to produce spectacularly while avoiding sacks and turnovers.

He has played differently the past two weeks. Against the Falcons, Keenum did not produce a pass play of more than 22 yards. His ability to complete his last 15 passes, and to throw two touchdowns in the red zone, made the lack of big plays moot.

But the trend continued Sunday at Carolina. He did not produce a pass play of more than 22 yards until late in the fourth quarter, when he hit Adam Thielen in stride for a 52-yard catch-and-run.

Have defenses found a way to suppress the Vikings' offense?

"I put a lot of that on me,'' Thielen said. "I missed plays that could have changed the whole concept of the game.''

"It's on us,'' Rudolph said. "There were plays to be made, and we didn't make them.''

They're right. Dropped passes are like mini-turnovers. The Vikings' drops cost them points, yards, first downs and further opportunities.

The Vikings concluded their five-game test with four victories and one close, frustrating loss. They remain overachievers with a chance to win the first seed in the NFC playoffs, and they likely will be favored, perhaps heavily, in each of their three remaining games.

But paranoia hovers over the franchise like a buzzing drone. A fan base that will never forget Wide Left or 12 Men In The Huddle — or, for older Minnesotans, four Super Bowl losses — was given reasons to worry Sunday.

Reiff's ankle. Remmers' back. A stumbling offense. And a quarterback who, at his career peak of popularity and efficiency, made a handful of plays to regret.

Jim Souhan's podcast can be heard at On Twitter: @SouhanStrib. •