Defense will decide which AFC heavyweight rules the conference

Four sublime quarterbacks - Tom Brady, Drew Brees, Brett Favre, and Peyton Manning - achieved something rare in the NFL. They beat all 32 teams at least once in the regular season or playoffs, including the franchises, like the Patriots for Brady or Packers for Favre, that benefited most from their greatness.

Patrick Mahomes might never play against the Chiefs, but barring a surprise eventual move, he has one club left to conquer. Mahomes will become the 10th NFL passer to defeat a 31st team, tying the likes of Aaron Rodgers and Russell Wilson, if the Chiefs prevail Sunday in his first matchup with the Vikings.

Mahomes has grander goals this season: He's aiming to lead the first repeat championship run since New England's Super Bowl triumphs of the early 2000s. So far, he’s gotten plenty of help from his defense.

Four 3-1 teams - the Bills, Chiefs, Dolphins, and Ravens - pace the AFC as Week 5 arrives. Optimally balanced, Baltimore, Buffalo, and Kansas City have great quarterbacks and also rank in the top five in points against and defensive expected points added per play, per Ben Baldwin's database. Miami scores at will but is vulnerable without the ball, as the Bills proved in last week's 48-20 beatdown.

Throwing to Travis Kelce and various unheralded wideouts, Mahomes hasn't performed to his usual brilliant standard. His completion percentage (64.3%) and yards generated per game (251.5) fall well below his career averages.

Two defensive standouts have picked up the slack. Star nose tackle Chris Jones has notched a sack per game since ending his holdout after the Chiefs lost the season opener. Trent McDuffie has dislodged two fumbles and ranks fourth among NFL cornerbacks with 10 stops, defined by PFF as a tackle that constitutes failure for the offense.

The Chiefs' defensive forte is that they get off the field. They've forced five punts per game, the No. 3 mark in the league. According to Baldwin's data, they're third in defensive EPA/play on third- and fourth-down snaps, up from 23rd in those situations in 2022.

Timely stops snuffed out Jaguars drives when Kansas City won 17-9 in Week 2. Cornerback Jaylen Watson sprinted from the defensive backfield on third-and-2 to truck Christian Kirk for no gain. On another third-down pass, McDuffie prevented Zay Jones from landing in bounds at the back of the end zone. Chris Jones sacked Trevor Lawrence and L'Jarius Sneed blanketed Calvin Ridley to foil fourth-down attempts.

Zach Wilson put up a career-best 105.2 passer rating against the Chiefs last week. Still, the Jets were blanked for the final 25 minutes of a 23-20 loss. New York ran 13 offensive plays in the span to Kansas City's 36. The K.C. defense helped Mahomes milk the clock, forcing two second-half punts and pouncing on the snap that Wilson muffed.

Reckless in Week 1 against the Jets, Josh Allen made smarter decisions in subsequent Bills blowout wins. When Allen humbled the Dolphins, he became the only quarterback besides Rodgers to amass 300 passing yards, four passing touchdowns, and a rushing score while maintaining a perfect passer rating.

The Bills' defense put the ball in his hands. They slowed Miami's explosive attack immediately following that offense's 70-point drubbing of the Broncos. Against Buffalo, Tua Tagovailoa's longest completion only went for 23 yards. He was sacked four times, twice on fourth down when a four- or five-man rush breached his protection.

Buffalo leads the NFL in defensive interceptions (eight), takeaways (11), and sacks (16) despite blitzing a mere 17.6% of the time, per Pro Football Reference. Defensive tackle DaQuan Jones, edge rusher Greg Rousseau, linebacker Matt Milano, and safety Micah Hyde all own top-20 PFF grades at their positions. The Bills have the talent at every level to withstand cornerback Tre'Davious White's Achilles tear.

Miami's defense looks flimsier. Stranded in solo coverage against the Bills, cornerback Kader Kohou failed to wrap up Stefon Diggs on a 55-yard touchdown catch and run. Kohou was flagged on a different scoring drive for interfering with Diggs 43 yards downfield. Justin Bethel bit on a fake and was left in the dust on Gabe Davis' TD.

The Dolphins can literally outrun their problems. Speedsters Tyreek Hill, De'Von Achane, and Raheem Mostert are responsible for the five fastest runs of the season, per Next Gen Stats. This trio has already housed 17 touchdowns. Tagovailoa feeds them the ball quickly (average time to throw: 2.34 seconds) while still managing to sling it long (average depth of target: 9.0 yards), inflating his own gaudy numbers (326.5 passing yards per game).

On the other side of scrimmage, the Dolphins rank last in defensive success rate, per Baldwin's data, and won't get to activate Jalen Ramsey from his knee injury until December at the earliest. Miami's most-used cornerbacks - Xavien Howard, Kohou, Eli Apple, and Bethel - have combined to allow a 73.5% reception rate when targeted, per PFF. That output won't cut it in the biggest games.

Elsewhere in the AFC, extinguishing offense is the Ravens' specialty. A full 27 seasons have elapsed since the franchise moved to Baltimore in 1996. In 10 of them, the Ravens fielded a top-three defense by points allowed.

Mighty again this year, the Ravens only gave up three touchdowns - none on the ground - through Week 4. They own PFF's No. 1 team coverage grade despite Pro Bowl cornerback Marlon Humphrey's injury absence. Safeties Kyle Hamilton and Geno Stone have teamed to snare three interceptions. Pressing the demolition button, Roquan Smith leads all NFL linebackers with three pass breakups and ranks in the top 10 at the position in sacks and stops.

QB rushing leader Lamar Jackson, the consummate dual threat, elevates Baltimore's offensive ceiling. By comparison, the Browns lack playmaking star power - Nick Chubb's out for the year and Deshaun Watson's right shoulder is ailing - but can stifle any opponent.

The NFL's best defense by EPA/play, Cleveland leads the league by huge margins in QB knockdown rate (18.9%), third-down stop rate (77.4%), and first downs conceded (37, or 19 fewer than the second-place Cowboys). Myles Garrett recorded the season's quickest sack in Week 3 by downing Ryan Tannehill within 2.27 seconds, per Next Gen Stats. He could wreck a contender's season in the wild-card round if the Browns qualify.

The tailspinning Bengals, meanwhile, haven't adjusted on offense or compensated defensively for the problems posed by Joe Burrow's calf strain.

Burrow's completion rate (57.6%), big-time throw rate (1.9%), and QB EPA/play rank (27th, sandwiched between Mac Jones and Kenny Pickett) are significant personal worsts. Meanwhile, the Bengals are 31st in rushing yards gained and allowed. Pride and the preservation of their playoff hopes are on the line Sunday against the Cardinals.

Every AFC South team is 2-2, threatening the Jaguars' divisional supremacy. C.J. Stroud's plucky Texans torched them in the air in a 20-point defeat.

Stingy in other games, Jacksonville's defense produced nine total takeaways in wins over the Colts and Falcons and the close loss to the Chiefs. Baiting Allen into turnovers, like the Jets did four times in Week 1, could help the Jags upset the Bills in London.

Subpar defensively throughout the Justin Herbert era, the Chargers need to tighten up while Herbert prepares to play through a finger fracture on his non-throwing hand.

Khalil Mack's evisceration of the Raiders was a nice development. Five of Mack's six sacks led to a punt or fumble, swinging possession and momentum in a 24-17 win. When the pass rush falters, the Chargers get exposed downfield. They rank last in passing yards allowed (299.8 per game) and yards allowed per completion (12.7).

Stiff tests await the Chargers in October. They host the Cowboys and visit the Chiefs in consecutive weeks. First, they're off Sunday as Kansas City faces the Vikings and Mahomes pursues his latest milestone.

Vikings quarterback Kirk Cousins is 0-3 lifetime against the Chiefs. Coincidentally, they would be the 31st team Cousins has ever topped. Extrapolated over 17 games, Minnesota's Justin Jefferson is on pace to gain 2,308 receiving yards and thereby obliterate the single-year record. Quieting him would confirm that this Chiefs defense is legit.

Nick Faris is a features writer at theScore.