Just when the NFL was enjoying a ratings rebound and an explosion of offensive firepower that has fans giddy over their favorite and/or fantasy teams, the league reverted to its bumbling ways in Week 13.

It began with a prime-time officiating fiasco by its most experienced crew.

The poor performance by referee Walt Anderson’s crew Thursday night sullied an otherwise classic Saints-Cowboys showdown that reminded everyone defense can be sexy, too.

Jaylon Smith’s helmet-to-helmet hit on Alvin Kamara was the most egregious non-call, one that Fox Sports rules analyst Mike Pereira called “a clear example of leading with the crown of the helmet.”

Just feet away from the illegal hit were field judge Terry Brown and line judge Byron Boston, both of whom kept their yellow flags tucked safely away as New Orleans coach Sean Payton went ballistic.

Just under the six-minute mark came the most crucial bad call.

With the Cowboys facing third-and-5 from the 50-yard line, Saints cornerback P.J. Williams tackled Cowboys receiver Cole Beasley a full yard shy of the first-down marker, but the officials said to move the chains.

Out of challenges, Payton was helpless to get the call reviewed, and because it was outside of 2 minutes and not a scoring play, the league’s hands were tied, too.

Payton had his own inexplicable blunder after the teams traded takeaways in the final minutes.

After Dallas got the ball back at the Saints 16 with 2:08 left, Ezekiel Elliott ran for 2 yards and Payton burned his last timeout three seconds before the 2-minute warning.

Had he waited, the Cowboys likely would have run twice, forcing the Saints to call their final timeout and running more time off the clock. A field goal would have left the Saints down six with about 45 seconds for Drew Brees to try to pull off some last-minute magic.

But the timeout at 2:03 meant the Cowboys could throw on second down knowing the clock would stop regardless once the play was over. A pass interference call gave them a first down and they ran out the clock.

The next day brought more bad news for the league when TMZ released surveillance video of Kareem Hunt shoving and kicking a woman in an altercation that ultimately led to the star running back’s release from the Kansas City Chiefs and landed Hunt on the commissioner’s exempt list.

On Sunday, Hunt told ESPN that the league had never interviewed him about the matter, which prompted the NFL to release a statement defending itself .

Hunt was cut the same day Washington Redskins executive Doug Williams apologized for calling linebacker Reuben Foster’s domestic violence arrest “small potatoes” compared to crimes committed by people in power.

The Redskins took plenty of heat after claiming Foster off waivers from the San Francisco 49ers, who released him Tuesday, three days after he was arrested and charged with domestic violence in Tampa, Florida.

Sunday’s games brought another slew of gaffes.

Most notable was the Los Angeles Chargers getting away with a blatant false start on a touchdown for the second time this season.

In October, Chargers right tackle Russell Okung wasn’t whistled for an obvious false start on a touchdown play against Cleveland, and shortly afterward, the NFL fired down judge Hugo Cruz for inadequate performance.

On Sunday night in Pittsburgh, the Chargers did it again , only this time it was right tackle Sam Tevi who clearly jumped early on Philip River’s 46-yard touchdown throw to Travis Benjamin.

“We’ve seen it before and it led to a dismissal. I certainly hope that doesn’t happen again,” said Pereira, noting “that was a miss that was on the same level as the one” in October.

Those seven points made all the difference in the Chargers’ 33-30 win over the Steelers, who fell to 174-1-1 when holding a 16-point lead at home.

“There was no explanation other than they missed it,” coach Mike Tomlin said afterward.

Tomlin cut off further questions about the officiating lest he open himself up to a fine from the league office. “I’ve sent enough money to New York,” he said.

The game ended in bizarre fashion as the Steelers jumped offsides three consecutive times, first on a missed field goal, then on a blocked attempt and finally on the game winner.

Pereira and fellow former NFL head of officials Dean Blandino said on Fox Sports that the crew could have awarded the Chargers the points even without the ball going through the uprights because of an obscure league rule prohibiting teams from repeatedly committing deliberate fouls to prevent a score.

Blandino said he would have invoked the rule.

“I think the rule book is clear. You give a warning and then after the warning, you award the score,” Blandino said.

Not all the bad calls were made by the men in stripes.

The New York Giants coaching staff, for example, must be regretting sending receiver Odell Beckham Jr. out on their “hands” team.

After the Bears kicked a field goal with 1:13 left to pull to 27-20, they went for an onside kick, which they recovered thanks to Beckham’s business decision not to get into the scrum for the recovery .

“I could dive in there and still not get the ball, so it was a very tough call,” an irritated OBJ said after the Giants pulled out the win in overtime on a day when he became the first player since 1924 to record multiple games with a TD pass and a TD catch in a single season.

“Nobody should even question me on my effort and my heart,” Beckham insisted. “That’s the last thing you can do. You can question me as a person, as a man, whatever you want to do. But my heart and my effort can never be questioned. Ever.”

Except when he doesn’t go for the football on the onside kick to seal the win.