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.

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,but the officials moved 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.