ATLANTA -- Because the McCourty twins are constantly ripping on each other in a good-natured way, as brothers do, it's hard to tell if and when they're ever genuinely critical of one another.

It was hard to tell about an hour after the Patriots won Super Bowl LIII, and I asked Devin McCourty about the play his brother made late in the third quarter. In a game where the final score was something out of bygone football era, 13-3, Jason McCourty's pass breakup on a sure-thing touchdown to Brandin Cooks ended up being one of the most crucial plays of the game.

"He blew it the first time," Devin yelled as he skipped into the Patriots locker room, almost as if he was hoping his brother would hear.

"He just did what he was supposed to do! He was supposed to do it the first time and they missed it!"

The first time?

Turns out the Rams ran the same play earlier in the game. It came late in the first quarter when coach Sean McVay had his 11-personnel grouping on the field and a bunch to the right of the formation. Quarterback Jared Goff was under center, as he often is.

When Goff dropped back, he faked a hand-off and surveyed the field. It was essentially a two-man route for LA. From the bunch, Robert Woods ran a deep-over route. From the opposite side of the formation, Cooks ran a post.

Deep-overs off of play-action have been a staple for the Rams all season as McVay and his team worked their way toward cementing themselves as owners of one of the most explosive offenses in football.

Understanding Goff's affinity for that route, and understanding his relative dearth of options on the play, the Patriots -- in quarters coverage, with defensive backs splitting the deep portion of the field into four zones -- jumped Woods with their two middle zone players: Devin McCourty and Jonathan Jones.

Gilmore, meanwhile, stuck with Cooks as the former Patriots receiver worked his way to the middle of the field. Jason McCourty played the opposite side of the field, guarding nothing but air in his zone. He was in no-man's land, and if Goff let one rip to Cooks in the middle of the field with Gilmore trailing, it might've been a touchdown.

That's what Devin was referring to when he playfully (maybe not so playfully?) said Jason "blew it the first time." But when Jason's chance came a second time against the same look, he made it count.

Late in the third quarter, with their 12-personnel grouping on the field, the Rams showed an identical formation: bunch to the right, under center, with Cooks in a tight split off the left tackle.

The play was essentially the same: Woods ran a deep-over; Cooks got vertical quickly; running back Todd Gurley went to the flat.

The Patriots were in their quarters look once again, and Jones and Devin McCourty jumped the deep-over again.

But this time, instead of Gilmore shadowing Cooks deep, as he did the first time, the All-Pro corner stayed in his zone nearest to the Patriots sideline. Woods was effectively triple-teamed, and Cooks was wide open.

In that moment, instead of playing the role of help defender, as he should have been back in the first quarter, Jason McCourty was New England's only hope of keeping Cooks from scoring.

Covering a whopping 19.5 yards in 2.4 seconds (reaching a top speed of 18.9 miles per hour, according to NFL Next Gen Stats), McCourty got to Cooks to separate him from the late-arriving Goff lob.

"Turning and running and hurrying up and trying to get there as fast as I can," Jason said Monday of his memories of the play. "Luckily I was able to get there in that split-second."

"It was a good play, man," Devin McCourty said. "I turned around like, 'Where's he throwing the ball? The over's covered. The post is covered.' And I turned around, and it was like, 'Oh damn.'

"But it was just great effort by [Jason] . . . He was already running to that play to be the second guy to help. But then when he saw him open, he just dropped his head and took off and used whatever he got left of that body to get there."

"Oh my God," Belichick said after the game. "That was a tremendous effort and a great play on the ball. It looked like [Cooks] was going to fair catch the ball. McCourty came out of nowhere to make that play."

"It just shows the relentless effort that Jason McCourty played with tonight," Duron Harmon said. "Not giving up on any play. The awareness he had to see that. That was something we had a little bit earlier, but [Cooks] wasn't that open. But all [Jason] did was run to the football, not give up. He made a great play, a four-point play right there."

LA kicker Greg Zuerlein eventually made a 53-yarder, but thanks in part to Jason, that would be about as close to a touchdown as the Rams would get the remainder of the night.

Part of Goff's confusion Sunday was that the Patriots were willing to play as much zone coverage -- like that quarters look during the McCourty-on-Cooks pass-breakup -- as they did. Under Belichick and Brian Flores, the Patriots played more man-to-man on a percentage basis than any other defense during the 2018 season.

But with two weeks to prepare and two weeks to tailor game plans, the Patriots broke one of their defensive tendencies to frustrate McVay and his young passer. At Mercedes-Benz Stadium, tin the most important game of the year, he Patriots secondary took on a different identity.

"We have a lot of smart football players on our defense," Devin said. "Lot of versatility from guys. And I think we've taken all challenges of trying to mix our game plan. That was hard for them. You look at our last four games, it's predominantly man-to-man, load the box. Everyone was kind of playing man-free or blitz-zero with no help.

"And we went out there to start the game -- and for most of the game we were in zone. We obviously still had our man in there on third down and at different times. But it was kind of a total change from what we had been running. We knew it would give them trouble. And I think it was one of those things, feelings-wise, we went in feeling really good about our game plan."

With the shift to more zone coverages, Jason became a significant part of that plan. He played all 63 snaps in his first Super Bowl, despite cracking the 60-snap mark just twice since JC Jackson became a starting corner in Week 13. Jackson, a man-to-man wiz in his first season as an undrafted player out of Maryland, played 29 snaps in the Super Bowl.

The defensive play of the game came with the Patriots playing man-to-man. It was one of those "blitz-zero" reps Devin referenced, when Belichick and Flores brought the house to force Goff into a bad throw that was picked by Gilmore late in the fourth quarter.

But the second-biggest defensive play of the night, the play that also happened to be most symbolic of New England's willingness to change styles on a week-to-week basis, was a zone look that might've won the game for Belichick and his team. Jason McCourty's pass breakup on Cooks's would-be touchdown in the third quarter would've given the Rams the lead, 7-3, and changed the entire tenor of the game.

Instead, the Patriots went on to score their only touchdown two drives after Jason McCourty's pass breakup, and they killed enough clock to make it hard on the Rams to come back from a double-digit deficit with a little over a minute left on their final possession of the fourth quarter.

"It wasn't really until they missed that field goal, the realization that there was nothing that they could do," Jason said. "We were gonna get the ball, take a knee, and that was going to be all she wrote.

"Literally, standing next to Dev on the field-goal block team. That [Rams] kick goes up, it's wide left, and we just looked at each other. I remember running to the sideline and screaming to my family in the stands and realizing that that was it. Super Bowl champ."

“It was 10 times better than both of the other Super Bowls," Devin said of winning one with his brother. "Better than I thought it would be."

Click here to download the new MyTeams App by NBC Sports! Receive comprehensive coverage of your teams and stream the Celtics easily on your device.