METAIRIE, La. — Something’s gotta give on Thursday night in Dallas.

The Cowboys’ Ezekiel Elliott has been the hottest running back in the NFL over the past three weeks, with 394 rushing yards, 531 yards from scrimmage and four touchdowns.

But the New Orleans Saints have had the NFL’s most stifling run defense all season, allowing just 73.2 yards per game. No running back has run for 70 against them.

Last Thursday night, Atlanta Falcons running backs Tevin Coleman and Ito Smith combined for just 6 yards on 12 carries.

“When you can hold a team to 1.6 [yards] a carry, they may as well not even try to run the ball anymore,” Saints defensive tackle Sheldon Rankins said of Atlanta’s average yards per rush, which was boosted by quarterback Matt Ryan’s two scrambles for 16 yards.

“Playing this game, if you can impose your will on someone by basically being able to tell them they’re not gonna run the ball and ‘there’s nothing you can do about it,’ it does a lot for your mentality,” Rankins said.

So when, exactly, did the Saints start having a run defense that could impose its will like this?

The Saints haven’t finished a season higher than 10th in the NFL in run defense since 1992, when the famed “Dome Patrol” sent four linebackers to the Pro Bowl.

And run defense has not been their signature during the Sean Payton-Drew Brees era. Even during their 2009 Super Bowl season, they ranked 21st. Last season they ranked 16th with many of the same players and the same defensive coordinator, Dennis Allen.

“Generally if you’re playing good run defense, it’s all 11, getting everyone to the football,” Payton said. “Generally that means everyone’s tackling. It can’t just mean eight or 10, and I think that’s been the case.”

That’s a simple and generic explanation, but also accurate. The Saints haven’t made any drastic scheme changes, and it’s not like they’re stacking eight and nine men in the box to sell out against the run.

They’re mostly getting elevated play throughout the front seven — from guys such as Rankins, who is having his best season in Year 3, All-Pro defensive end Cameron Jordan and veteran linebacker Demario Davis, who has proved to be an outstanding free-agent signing, among others.

“It’s something we’ve harped on since the offseason. It’s something we’ve obviously taken the time to try to perfect. And it’s something we want,” Rankins explained. “It’s something that was a goal at the beginning of this season to be the No. 1 rush defense — and we’re well on our way. But it’s another challenge this week with the Cowboys’ run game … 130-some yards per game, at [their] home. So it’ll be fun.”

Rankins noted the defensive line’s development in Year 2 under defensive line coach Ryan Nielsen. And the linebacking corps has undergone even more of a transformation in its second year under veteran coach Mike Nolan.

Not only is Davis a newcomer, but second-year pro Alex Anzalone played in only four games last season before suffering a season-ending shoulder injury. And veterans A.J. Klein and Manti Te’o arrived as free agents in 2017.

The Saints’ coaching staff made a surprising decision to move Anzalone inside to middle linebacker this season, even though he began his career on the weak side. And they moved Davis to the weak side after he spent most of his career in the middle.

Coaches and players have downplayed those moves, saying the positions are similar and both require versatility. Still, they’ve obviously found an effective way to make all the pieces fit. Klein starts on the strong side and plays most often with Davis in New Orleans’ two-linebacker sets.

The Saints actually have five players who have started in the NFL as the signal-calling middle linebackers, including versatile backup Craig Robertson.

“It’s a room of alpha males and alpha lions,” said Davis, a 6-foot-2, 248-pounder who leads the Saints with 76 tackles after leading the New York Jets with 135 last season. “I always thought of myself as more of a hybrid player. I feel like I can play on the edge. I feel like I can play in the middle and get everybody lined up. And I feel like I can play on the outside and play in space guarding running backs and tight ends.

“I told the coaches when I first got here, whatever you need me to do, I’ll do it.”

That he has. Davis said he has spent more time covering tight ends and backs this year than usual, while also blitzing at times. He ranks third on the team with nine tackles for loss, is tied for third with eight quarterback hits and has three sacks and two forced fumbles.

“Obviously Demario is great against the run. He’s everything you look for in a linebacker,” Klein said. “He’s able to cover in space, play the run, play the pass. I mean, he’s a complete player. So obviously he’s added a lot to our defense, and he’s added a lot to our versatility.”

The Saints will need all the versatility they can muster against the 6-foot, 228-pound Elliott, who is looking as good as ever in recent weeks.

The Saints held up well against the likes of Todd Gurley (13 carries for 68 yards and a TD, six receptions for 11 yards) and Saquon Barkley (10-44 and a TD, 6-56). But Elliott provides a similar challenge.

“You wouldn’t think a guy that runs that powerful would have the breakaway speed he does,” Rankins said. “He’s able to run away from guys and get to the edge and create huge plays for that offense.

“Overall, [Elliott is] one of the top five most talented backs in this league. So we’ve definitely got our hands full.”