ORCHARD PARK, N.Y. -- Four games into the season and the Patriots are undefeated. This isn't news; New England has six Super Bowl titles since 2001, which coincides with the Bill Belichick-Tom Brady ascendancy, and everyone has heard this story often enough to recite it in their sleep.

What is news, however, is that the Patriots' defense is markedly better than the Brady-led offense, and that was on full display Sunday against an upstart Bills team that also came into the game with a 3-0 record. When it was over, New England eked out a gritty 16-10 victory primarily thanks to its defense and special teams.

Brady finished 18 of 39 for 150 yards with no touchdowns and a second-quarter red-zone interception that could've put the game away before intermission. He rarely attempted a pass more than 10 yards downfield, and his longest completion of the day -- a short crossing route Josh Gordon turned into a 31-yard gain -- came after the Bills' defensive back fell down. It's at this point that we need to credit the Bills' defense, which was outstanding, but whose performance was overshadowed by a Patriots outfit that has been damn-near perfect on the year.

The New England defense came into the week ranked No. 1 overall, according to Football Outsiders, and was No. 1 against the run and the pass. The Steelers' high-powered offense was no match for this unit in Week 1 (the Pats won, 33-3), and in more predictable finishes, Dolphins and Jets also had their doors blown off in the weeks that followed (43-0 and 30-14, respectively). The Bills would be the Patriots' toughest matchup to date, ranking ninth overall, 18th on offense and sixth on defense.

Buffalo was also playing at home and off to its best start since 1992 when it started 4-0, finished 11-5 in the regular season and made its third Super Bowl appearance in four years (we'll leave it at that). Second-year quarterback Josh Allen came into the game having shown signs of growth and maturity each week.

But this wasn't the Jets, Giants or Bengals, outfits that were a combined 1-8 heading into Week 4. This was the Patriots, who have won Super Bowls with decidedly less talented defenses. In 2016, New England's D ranked 16th in the regular season and looked overwhelmed against the Falcons in Super Bowl LI only to overcome a 25-point deficit. A year later, the defense ranked 31st and again made it to the Super Bowl before succumbing to Nick Foles and the Eagles. And last seaon's Patriots D again ranked 16th, but you wouldn't have known it to watch them dominate the Rams in Super Bowl LIII, holding the NFC's best offense to three measly points.

It was such a surprising performance that we wrote about it after the game -- the Patriots' defense took over, Sean McVay and the Rams were helpless to do much about it, and much of what we heard from New England players afterwards was that they couldn't figure out why anybody would think they couldn't play like this.

Turns out, it was a fair complaint, and one that has carried over into the 2019 campaign. Except that, seven months later, this defense is the engine that's driving this team forward. As Brady and the offense struggled to move the ball, the defense intercepted Allen on the first drive.

It's easy to blame Allen here -- the Patriots like to leave Devin McCourty in the middle of the field as a single-high safety and Allen somehow didn't see him, but credit McCourty for high-pointing the ball and coming down with his fourth interception of the season (he had just four interceptions in his previous 68 games combined).

The defense forced a Bills three-and-out on the next series, and that led to this:

Buffalo punted again on its next drive, and on the drive after that Allen tossed another interception, this time a woefully underthrown ball intended for Zay Jones that J.C. Jackson hauled in.

You could argue that a properly thrown pass would have cleared Jackson and found its way to Jones, who would've sauntered into the end zone. But how often have we seen Allen do that? Not nearly enough, and the mistake cost Buffalo points.

The Bills did score a touchdown to start the third quarter, something no other offense has been able to do this season against the Pats, but it required a nine-play, 75-yard drive in which Allen had to complete passes of 23, 15, and 16 yards, and then barely cleared the goal line on a quarterback sneak on fourth-and-goal.

Put another way: Nothing is easy against this defense, which explains why the Bills were blanked over the final 24:23 on six drives that went like this: punt, interception, downs, punt, punt, interception. Allen was forced from the game early in the fourth quarter after taking a nasty hit to the head from cornerback Jonathan Jones.

"There's no room in football for that," Bills coach Sean McDermott told reporters afterwards. :It's a shame to see a player like Josh, or any player, go down from a hit like that."

And Bills safety Micah Hyde wondered why Jones wasn't ejected.

"That's the first thing that came out of my mouth on the sideline: If one of us did that to 12, we wouldn't have been in the game anymore," Hyde told reporters in the locker room. "There's no way. There's no way we would've continued to play in that game."

Matt Barkley replaced Allen and completed a 28-yard pass to John Brown deep in Patriots territory. But six plays later, he missed Zay Jones in the end zone on fourth down and New England took possession. But as had been the case all afternoon, the Bills' defense kept Brady under wraps and Buffalo three more times in the final quarter. But Barkley, who finished 9 of 16 for 127 yards, tossed one final pick -- Buffalo's fourth on the day -- to seal the Bills' first loss of the season.

True to form, Belichick was a man of few words during his postgame press conference, but he took a moment to praise his defense.

"We had good team defense," he said, adding: "I didn't think that ball was ever going come down on the last interception. [Jamie Collins] almost fair caught it."

Linebacker Kyle Van Noy pressured the quarterback on that play, just as he had done throughout the game. The "we get no respect" talking point is a bit much at this point but Van Noy is one of the most underrated players in the league. On Sunday, he led the team in tackles (6), sacks (2) and quarterback hits (3), and he forced two fumbles.

We're reminded of something he said moments after the Patriots beat the Rams in the Super Bowl, when there were plenty of doubters that even Belichick could slow down McVay and Co.

"We still have a bad defense?" Van Noy asked at the time. "Like I said earlier, we have elite football players. We aren't stars over here we just show up to work and keep grinding."

It's probably safe to start making the case that these guys are, in fact, stars. Even if they don't want to hear it.