Where the hell did this come from?

In the middle of September, the New Orleans Saints were a punchline. Surrendered a league-high 29.8 points per game in 2015, ranked 31st the next year with 28.4 points allowed per game. Gave up 65 more points in back-to-back losses to the Minnesota Vikings and New England Patriots to start the season.

A horrible defense had somehow gotten even worse. At that point, they’d lost five of seven. It looked as though they were headed toward a fourth consecutive losing season.

And then everything changed. The Saints haven’t lost since, as they continue to ride an eerily quiet six-game winning streak. They’re just the third team in NFL history to win six straight games following an 0-2 start, joining the 1993 Dallas Cowboys and the 2007 New York Giants (Super Bowl champions, both of ’em).

And while future Hall of Fame quarterback Drew Brees and the league’s sixth-highest-scoring offense is a major reason why this has happened, the remarkable turnaround has actually had a lot more to do with that oft-maligned D.

Dennis Allen’s group has held opponents to 17 or fewer points in five of those six games and 13 or fewer points in four of them. Prior to this stretch, they hadn’t done that on a single occasion in their previous 42 games, dating back to 2014.

Since Week 3, they’ve allowed just 12.7 points per game on defense, excluding a pair of Detroit touchdowns which came on defense and special teams. That’s the lowest mark in the NFC.

In terms of DVOA (Defense-adjusted Value Over Average), Football Outsiders ranked the Saints dead-last in football in 2015 and 31st in 2016. But this year, they’ve shot up to the No. 8 spot in that category.

Somehow, the D has gone from liability to asset overnight. But we shouldn’t be too shocked, because that unit had been rebuilding for several years and certainly has the talent. Their last two first draft picks, cornerback Marshon Lattimore and defensive tackle Sheldon Rankins, have excelled, with Lattimore already looking like a shutdown corner and a defensive rookie of the year frontrunner. Veteran pass rusher Cameron Jordan is having a career year, talented safety Kenny Vaccaro has emerged as a strong playmaker and free-agent addition Alex Okafor has exceeded expectations up front.

Will they sustain this pace? It’s unlikely. They’re still not very deep, and they have certainly benefited from facing some weak offensive opponents. They shut out Miami, but everybody does that. They drew the Panthers when that team was in a rut, they met the Packers without Aaron Rodgers, and the Bears and Buccaneers have two of the league’s worst offenses. The Lions are the only decent offensive team they’ve faced since Week 3, and they struggled most of the day against that unit.

But the good news is that D doesn’t have to keep this up in order for the Saints to compete. They don’t have to dominate, they just have to avoid getting dominated. And in the process, they have to try to get the ball into Brees’ hands as much as possible. That was the formula when this team won the Super Bowl in 2009, and it’s a good sign that even when they struggled to slow the Lions down they still generated five takeaways.

They’ve had at least one takeaway in every game during this stretch, with 12 in total. They had zero in the first two weeks.

There’s room for error so long as you can force some errors. The Saints haven’t just won each of their last six games, but they’ve won each of their last six games by at least eight points. And there’s reason to believe we haven’t seen the best of Brees, who always winds up with 30-plus touchdown passes and 4,800-plus yards but is well short of those paces at the midway pole this season.

The 38-year-old was on fire the last two weeks, though, posting a 121.4 passer rating while completing 81.8 percent of his passes against not-shabby defenses.

With his pass protection improving and rookie running back Alvin Kamara emerging, it’s possible the he and the Saints could actually get better in the second half of the season.

“I really don’t think we’ve scratched the surface on how good we can be,” Brees said this week. And he might be right. Get used to the Saints being good again. This isn’t a flash in the pan. They’re here to compete as a wildly unexpected contender in this wildly unpredictable NFL season.

About Brad Gagnon

Brad Gagnon has been passionate about both sports and mass media since he was in diapers -- a passion that won't die until he's in them again. Based in Toronto, he's worked as a national NFL blog editor at theScore.com, a producer and writer at theScore Television Network and a host, reporter and play-by-play voice at Rogers TV. His work has also appeared at CBSSports.com, Deadspin, FoxSports.com, The Guardian, The Hockey News and elsewhere at Comeback Media, but his day gig has him covering the NFL nationally for Bleacher Report.