Throughout the first three months of the 2018 season, all you heard about throughout the NFL (and justifiably so) was that offenses had shot so far past defenses schematically, that defenses had no chance to catch up. Points were being scored and yards were being gained at a record pace, and when the Rams beat the Chiefs 54-51 at the end of Week 11, it marked the only time in NFL history when both teams had eclipsed the fifty-burger mark in the same game.

Meanwhile, defenses were running around like proverbial headless chickens, doing really dumb things in the red zone like playing all their cornerbacks off and leaving receivers wide open due to inflexible coverages. The Jaguars, who had the NFL’s best defense in 2017, have been victimized by their own defensive breakdowns all season, and they’re not the only team who has seemed singularly ill-equipped for a set of offenses more dynamic and variable than ever.

But in December, a funny thing happened on the NFL’s way to turn itself into the Big 12: Offenses started regressing heavily, and defenses started to catch up. According to Football Outsiders’ Aaron Schatz, the NFL’s Defensive DVOA (FO’s primary opponent-adjusted efficiency metric) has declined since the end of Week 12 from 1.7% to -6.1%. Since it’s a defensive stat in this case, DVOA is better when it’s negative. And as ESPN’s Trey Wingo points out, the 66 touchdowns scored in Week 15 marked nine fewer touchdowns than any other week this season.

What’s the reason for this sudden defensive dominance and offensive regression? One can point to several factors.

First, it makes sense that after a first half of the season in which they were made to look like innocent bystanders, defensive coordinators would start to pull their heads out and be more aggressive. The most cursory eye test would tell you that defenses are playing more aggressive coverage when they need to, especially in the red zone, and forcing opposing quarterbacks to make more contested throws. Defenses are certainly playing more match coverage, which they were not doing nearly enough early in the season, much to the dismay of many NFL analysts.

In contrast, there’s what’s happened to the Rams over the last three weeks. Los Angeles head coach Sean McVay loves when defenses play his receivers aggressively, because his offense is designed to exploit tight coverage with natural rubs and one-on-one mismatches. As I wrote yesterday, defenses playing the Rams are now backing off into more multiple coverages, forcing quarterback Jared Goff to process beyond his first read—something that Goff, at this point in his career, isn’t equipped to do play after play.

From Weeks 13-15, including Sunday night’s 30-23 loss to the Eagles, Goff has completed just 72 of 131 passes (a 54.96% completion rate) for 726 yards, one touchdown and seven interceptions—a massive downturn from previous weeks.

It’s not just happening to young quarterbacks, either. Consider the case of Drew Brees. Last we saw of the future Hall-of-Famer, he was neck-and-neck in the MVP discussion. But over his last three weeks, Brees has been muted as we’ve rarely seen before. From Week 13 through Monday night’s 12-9 win over the Panthers, Brees has completed 65 of 94 passes for 531 yards, two touchdowns, and three interceptions. That gives him a paltry 5.6 yards per attempt average, when his YPA from Weeks 1-12 was 8.8. Teams are realizing that the Saints don’t have a ton of speed among their receivers, they’re playing those receivers tightly, and Brees is having far more difficulty making deep throws.

So, if the Saints’ most important player is in statistical trouble, does that negate their Super Bowl chances? Not exactly.

Schatz also points out that for Sean Payton’s team, a major defensive turnaround has mitigated any offensive issues. Since Week 10, the Bears have the NFL’s best defense, and that’s no surprise, given what they did to Goff and the Rams in Week 14. But over that time, the Saints have finished second in Defensive DVOA.

And if you’re a firm believer in momentum, that’s good news for a Saints team that has spent most of Brees’ career there asking him to carry the franchise while the defensive performances have ranged from average to abysmal.

Why have the Saints been so good on defense? The entire unit has improved, but the coverage over that time has been especially exceptional. Per Pro Football Focus, in the first nine weeks of the season, New Orleans cornerbacks allowed 12 touchdowns and picked off just two passes. Since week 10? Just two touchdowns allowed, and four picks, and no touchdowns allowed at all in the last three games.

Eli Apple, who made a crucial interception in Monday night’s game, has allowed just 22 catches on 44 targets since Week 10. He has allowed one touchdown and has two picks. In the first half of the season with both the Saints and Giants, he was a far less effective player, and this trend seems to be going on around the league.

So, if you’re still worried about the NFL turning into a defenseless league, it might be time to put down the torches and pitchforks. Those defenses that looked so helpless in the first half of the season are starting to lower the boom… just in time for the stretch run and the postseason.