32 things we learned from Week 4 of 2021 NFL season: More than Tom Brady's Patriots showdown

The 32 things we learned from Week 4 of the 2021 NFL season:

1. Who's No. 1? After trouncing their division rival (and previously undefeated) Los Angeles Rams, the Arizona Cardinals have emerged as the league's only 4-0 team – on a day when the Carolina Panthers and Denver Broncos were exposed as products of their early easy schedules – though the Cards could be joined by the Las Vegas Raiders by the end of Monday night. Still, who had Cards-Raiders as their Super Bowl 56 picks? (And does anyone want that now?) But give these teams their due, especially as other perceived favorites and risers stumble.

2. What's the No. 1 regular-season game? Maybe of all time in terms of the buildup? Had to be Tampa Bay Buccaneers vs. New England Patriots – Tom Brady vs. Bill Belichick at Gillette Stadium after 20 years and six Super Bowl titles together – on Sunday night. What didn't it have? TB12 being warmly embraced by the Foxborough faithful before kickoff before getting a smattering of boos once the game started. The GOAT, Brady, against the first-round QB, Mac Jones, who effectively replaces him. Bad weather. Some poor officiating, especially some calls that nearly vaulted the Patriots to victory on their final drive. Brady wresting the NFL career mark for passing yards from Drew Brees. The return of Richard Sherman to the NFL on a night when he tied for the Bucs team lead with seven tackles. So many new Patriots, who didn't play with Brady (TEs Hunter Henry and Jonnu Smith, OLB Matt Judon) making their presences felt. Tampa's secondary becoming further depleted by injuries. Bucs coach Bruce Arians turning 69. The briefest of postgame exchanges between Belichick and Brady – they met privately for 20 minutes after the game – followed by a far lengthier embrace from New England offensive coordinator Josh McDaniels while the QB was hugged by seemingly dozens of ex-mates. And there was the final result, Bucs over Pats 19-17, allowing Brady to join Brees, Brett Favre and Peyton Manning as the only QBs to beat all 32 teams ... thanks to a 56-yard Nick Folk FG attempt that banged off the upright. What a night.

2a. And maybe the most amazing stat of Week 4: Brady, who had a pedestrian 269 passing yards, rushed for 3 ... or 4 more than the Patriots had collectively. Naturally.

2b. Now 1-3, New England and the balance of the AFC East now trail the first-place Buffalo Bills by two games.

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3. Largely lost amid all the Brady-Belichick hype was the misfortune of Bucs TE Rob Gronkowski, whose fractured ribs (suffered in Week 3) prevented him from likely enjoying his own hero's welcome Sunday night.

4. Back to Arizona. One noteworthy aspect of the Cardinals' so-called "Air Raid" offense during Sunday's win? They threw the ball 32 times, but ran it 40 times – and for 216 yards and two TDs. QB Kyler Murray (268 yards and 2 TDs passing and 39 rushing yards) may now be the current favorite for MVP honors as the face of this team, but Kliff Kingsbury's squad is proving very multi-faceted.

4a. Since moving to the Phoenix area in 1988, the Cardinals have only started 4-0 one other time – remarkably in 2012 ... when they finished 5-11.

4b. The Raiders haven't begun 4-0 since 2002 ... when they eventually lost Super Bowl 37.

5. Early frontrunner for NFL defensive player of the year? Gotta be Dallas Cowboys CB Trevon Diggs, who picked off two more passes and now has five this season (including at least one in every game). Don't expect Diggs to stay on a full-season pace for 21 picks – he had three as a rookie in 2020 – but it might not be long before he could legitimately threaten Hall of Famer Dick "Night Train" Lane's single-season record of 14, a mark that has stood since 1952 and is generally regarded as one of the league's most untouchable standards.

6. Cowboys QB Dak Prescott has thrown for 238 or fewer yards in each of his past three starts – including 188 (with 4 TD passes) in Sunday's win over the previously unbeaten Panthers – but Dallas has won all three. Should tell you something about the importance of balance. 

7. New York, NEW YORK! The Giants and Jets both got off the schneid with their first wins of 2021 on Sunday – which was also the first time ever both Big Apple teams won in overtime on the same day.

8. Also, Buffalo cruised 40-0 past the Houston Texans ... meaning, yes, New York actually went 3-0 in Week 4. (But New Jersey was only 2-0.)

9. Amazing how far the New Orleans Saints' passing game has evaporated, encapsulated during the loss to the Giants. New York had three receivers with more than 75 receiving yards, while the Saints had none.

10. Bummer for the Big Easy to finally reopen the Superdome in the wake of Hurricane Ida only to see the home team Saints lose.

11. Pittsburgh All-Pro OLB T.J. Watt sacked Aaron Rodgers twice, Watt's first sacks in Wisconsin since he was a Wisconsin Badger in 2016.

12. But Rodgers improved his career record against the Steelers to 2-1 in the Green Bay Packers' 27-17 win – the first time Rodgers (248 yards and 2 TDs passing, 1 rushing TD) had faced Pittsburgh since winning Super Bowl 45 following the 2010 season and first time he'd seen the Steelers at Lambeau Field.

13. Despite the setback to the Cowboys, new Panthers QB Sam Darnold still has more wins (3) this season than the Jets and Giants – combined.

14. Darnold also leads the NFL with five rushing TDs. No other QB has ever scored that many times on the ground in his team's first four games. Lamar who?

14a. Darnold had five rushing TDs total during his first three seasons with the Jets.

15. Remember waaay back in preseason, when we were largely praising the play of rookie quarterbacks while counting the drops of Cincinnati Bengals WR Ja'Marr Chase? How times change. Chase, 21, is the youngest to have at least four TD grabs in his first three games and was named the NFL's offensive rookie of the month for September.

16. Meanwhile, those rookie QBs have largely stunk to high heaven, though the Jets' Zach Wilson and Chicago Bears' Justin Fields both notched wins Sunday. Still, collectively, they're 3-13 through four weeks.

17. The next time you hear coachspeak about wins and losses being paramount and stats being for losers? Take it with a grain of salt. The Baltimore Ravens had little trouble handling the formerly unbeaten Broncos 23-7 in Denver. But coach John Harbaugh's decision to run QB Lamar Jackson on the game's final play (for 5 yards) rather than go into victory formation was a bit laughable. However ... Jackson's gain extended Baltimore's streak of consecutive games with at least 100 rushing yards to 43, tying the NFL record. Harbaugh admitted after the game, "That’s one of those things that’s meaningful. ... It’s a very, very tough record to accomplish."

17a. But give Jackson, who battled a bad back last week, credit – his arm (316 yards, TD) was the main element of the Ravens offense.

18. Seattle Seahawks QB Russell Wilson notched his 100th career regular-season win in his 148th start. Wilson, who has never missed a game since being drafted in 2012, joined Peyton Manning as the only players to reach the century mark in victories in their first 10 seasons.

COVID-19. Yes, it's still a problem in the country at large and, specifically, in the NFL. Just ask starting Seahawks TE Gerald Everett, who missed Sunday's game while on the reserve/COVID-19 list.

20. Watch out for the Cleveland Browns' ascending defense, which has allowed 13 points and 292 yards – total – over the past two weeks. Sunday's lockdown of the normally explosive Minnesota Vikings was far more impressive than Week 3's wipeout of the Chicago Bears.

20a. Student (Kevin Stefanski) > mentor (Mike Zimmer) ... at least this Sunday.

21. Is there a better "Slash" in today's NFL than Atlanta's Cordarrelle Patterson? He led the Falcons in rushing (34 yards on 6 carries) and receiving (82 yards on 5 receptions) while scoring a career-high three TDs. The All-Decade special teamer also averaged 26 yards on three kickoff returns for good measure.

22. All you folks who drafted Kansas Chiefs TE Travis Kelce (23 yards Sunday) in the first round must be pretty steamed watching the likes of Bills TE Dawson Knox and the Bengals' C.J. Uzomah scoring two TDs in Week 4. Lesson learned? Maybe none ... or maybe just stream fantasy tight ends.

23. Detroit Lions QB Jared Goff is playing much better than he did as a rookie with the Rams in 2016 ... but he's riding a seven-game losing streak for the first time in five years.

23a. Of course, Goff has won six in a row against the Cardinals. (See what we did there, Rams fans?)

24. The Bears won the battle against Detroit (again) on Sunday, but may have suffered a crippling blow if RB David Montgomery's knee injury is serious. Montgomery rushed for 106 yards and two TDs and has arguably been the team's best player this season. Next man up would be Super Bowl 54 hero (for the Chiefs) Damien Williams.

25. Reminder that NFL goal lines circumnavigate the entire world. Washington RB J.D. McKissic illustrated this on his game-winning 30-yard TD catch and vault in Atlanta.

26. The Jacksonville Jaguars have now lost 19 consecutive games. They trail only the 1976-77 expansion Buccaneers (26) for the longest losing streak in the Super Bowl era (since 1966) and will own the second-worst skid to themselves if they fall to the Titans in Week 5.

26a. New Jags coach Urban Meyer had never lost four in a row in his career ... until now.

26b. New Jags QB Trevor Lawrence has been on the losing side of his first four NFL starts after losing four games in high school and college ... combined. He went 86-4 between Cartersville (Ga.) High School and Clemson before going pro.

27. The Jets entered Sunday with six sacks but took down Tennessee Titans QB Ryan Tannehill seven times.

27a. And how about this nugget from Elias: Jets defenders Quincy and Quinnen Williams became the first brothers to record sacks in the same game for the same team since the stat became official in 1982.

28. Is there a more disappointing team right now than the Dolphins, losers of three in a row? Miami's obviously been hurt by the absence of injured QB Tua Tagovailoa, but they haven't even looked competitive in two of the past three weeks.

29. Nice job to the NFL schedule makers, who finally delivered a nice Thursday matchup (Jaguars-Bengals) between teams that don't get much press but needed to be slotted under the prime-time lights at least once this season. Cincinnati QB Joe Burrow and Jacksonville counterpart Lawrence both looked like players who could be among the league's leading lights in a few years. Cincy's 24-21 win was a nice palate cleanser after Week 3 served up Panthers-Texans on "Thursday Night Football." Hopefully the league's scheduling supercomputers will learn in the future to give us more Burrow vs. Lawrence – and maybe Darnold vs. the Jets, or Texans facing the ex-Texans (DeAndre Hopkins, J.J. Watt and the rest of the Cardinals) – so we can enjoy as much drama and subtext as possible with these required one-off appearances.

30. And overall, the games have been really good ... as usual. For the fifth time in NFL history, at least one contest has gone to overtime in each of the first four weeks of the season. And already at this point of the campaign, 15 games have featured a game-winning score in the final minute of regulation or in overtime – the most through the first four weeks of a season since the 1970 AFL-NFL merger.

31. Welcome back to Chiefs All-Pro WR Tyreek Hill, who had 19 grabs for 267 yards and one TD through three weeks as opposing defenses tried to limit his damage on deep shots. The Philadelphia Eagles couldn't replicate that bend-but-don't-break approach to Hill on Sunday as he exploded for 11 receptions for 186 yards and three scores in K.C.'s 42-30 get-well win.

32. And let's keep it 100 here for Andy Reid, given Foxborough, Mass., wasn't the only site of a notable NFL reunion Sunday. With Reid's win over the Eagles, his former team, the Chiefs coach became the first head man to win at least 100 games with two different franchises. Well done (and well timed), Big Red.

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Follow USA TODAY Sports' Nate Davis on Twitter @ByNateDavis.