In one corner of the visiting locker room inside Gillette Stadium, a Chiefs cornerback is explaining how he baited the greatest quarterback of a generation, if not ever, into a throw. How he duped him into an interception.

In another, there's a Chiefs safety having a conversation with a reporter about how they just knew what routes were coming. How homework sparked the game-sealing pass break-up.

And in the middle of it all, there's one more defensive back trying to ensure that not all of the inner workings of the Chiefs' defensive game-plan are publicized.

"Hey, hey, hey," Kendall Fuller cautioned his teammates. "We might play these guys again."

The 2019 Chiefs are different than 2018 Chiefs in trackable ways ... and those that are less quantifiable. In fact and opinion. In personnel and coaching staff.

But nowhere are they more different than the back end of the defense. In this case, that difference equates to improvement. It goes beyond athleticism and ability to make plays. It's the preparation and intellect to know exactly where to be and exactly when to be there.

The effects are showing up week after week. In pass break-ups. In game-changing turnovers.

On Sunday, as the Patriots faced a fourth-down attempt to tie the game late in the fourth quarter, receiver Julian Edelman jogged toward his slot position on quarterback Tom Brady's left side. Chiefs cornerback Bashaud Breeland joined him there and progressed through what he learned in his pre-game film work.

Then he knew what route to expect.

"I knew I was getting one of two routes -- it was process of elimination coming out of the huddle," Breeland said. "I knew he was giving me a (corner) or an over.

"And when I lined up in front of him, I could see him and Brady — they weren't running an over, not with a blitz; he wouldn't have time to throw it over there. So it had to be a 7 (corner), where he could throw it where the defense couldn't really get to it. So I just played the 7."

The Steve Spagnuolo-led defense studied Edelman's route tree throughout the week. He likes to run the corner — also known as the 7 route — when the Patriots are in the red zone. It's some of the bread and butter of the Patriots' offense post-Rob Gronkowski. The Chiefs secondary communicated it on the field before the snap.

An even better sign? Some players are no longer requiring communication on the back end. They just know. They trust.

A week earlier, safety Tyrann Mathieu left his man-to-man coverage against the Raiders and intercepted a pass. Raiders quarterback Derek Carr acknowledged being mystified by what Mathieu had done on the play. But Mathieu said he recognized the play pre-snap, and he knew safety Juan Thornhill would be there to cover his man, just in case. He wouldn't have attempted that maneuver early in the season, he said, but he's gained trust with Thornhill.

The secondary didn't lose often in Sunday's win in New England, other than a pair of trick plays, both with Breeland as a victim. The Chiefs felt satisfied the Patriots needed to delve that deep into the playbook to find an answer, because they had Brady rattled otherwise.

Breeland intercepted Brady in the first half. He was criticized on the telecast for getting beat and then making up for it. But that's not how it happened. The Chiefs were in a cover-3 look. Breeland pressed his receiver to lure Brady into thinking it was man-to-man, a move that appeared to work when Brady fired to what he believed would be an open receiver. But Breeland slid back into his cover zone after the press.

It fooled Brady. It fooled the telecast.

"We were in a zone — I press-bailed," Breeland said. "So he really thought we were in man. He thought I was on Julian and was going to follow Julian Edelman. He thought 'ain't nobody there.'

"It's what I was supposed to do. But the way I played it, it looked like I played it wrong."

The end result: The Chiefs made another play they quite simply did not appear capable of making a year ago.