Through six weeks of the 2019 NFL season, the New England Patriots (6-0) and San Francisco 49ers (5-0) are the only two teams to sustain unblemished records. The Niners are off to their fourth 5-0 start in franchise history and their first since 1990.

It's the fourth time the Patriots have started 6-0 in franchise history—all coming under the tutelage of head coach Bill Belichick and quarterback Tom Brady. The Patriots previously started 6-0 during their 2004 Super Bowl championship season, in their perfect regular season of 2007, and most recently in 2015, a year they began 10-0.

New England has the most winning streaks of six or more games since 2001 with 14. Speaking of streaks, the Patriots have won 11 straight games dating back to last year (including the postseason). They have won their past 16 home games, tied for the third-longest stretch in team history.

We will look at how the Patriots and 49ers are dominating, and more, in the six takeaways from an entertaining Week 6 in the NFL.

1. Patriots' defense maintains historically dominant pace

The Patriots are undefeated, largely due to their defense playing at a historical level. The special teams unit is also performing exceptionally well.

In the Patriots’ 35-14 victory over the New York Giants on Thursday night, the defense and special teams accumulated three interceptions, one fumble recovery, one blocked punt, one sack, and two touchdowns.

The first touchdown came on a blocked punt scored by rookie defensive end Chase Winovich.

The second score came on a forced fumble by Jamie Collins. Kyle Van Noy recovered the fumble and took it to the house for the TD.

Through six games, the Patriots have amassed 14 interceptions, two fumble recoveries and 25 sacks. They allowed their first passing touchdown of the season on Thursday night, a remarkable feat in a pass-dominant league.

New England has posted a +142 point differential. The defense and special teams have totaled five TDs.

In defeating Daniel Jones and the Giants, Bill Belichick improved to 12-0 against rookie quarterbacks at Gillette Stadium.

Also of statistical relevance, Tom Brady passed Peyton Manning for No. 2 on the all-time passing yards list. Brady has thrown for 72,257 yards in his legendary career, trailing only Drew Brees.

2. Backup QBs Kyle Allen, Teddy Bridgewater still unbeaten

The Carolina Panthers and New Orleans Saints suffered major blows in Week 2 when their starting quarterbacks went down with injuries. Carolina's Cam Newton, the 2015 NFL MVP, has been sidelined with a foot injury. Drew Brees, the Saints' signal caller and former Super Bowl MVP, tore a ligament in his thumb and has been out ever since. Withstanding these injuries, both the Panthers and Saints have rallied behind their backup quarterbacks.

Undrafted second-year QB Kyle Allen improved to 4-0 on Sunday as a starter this season for the Panthers, while Teddy Bridgewater has won all four of his starts for the Saints.

Impressively, Allen has yet to throw an interception in his career. Allen, who started the regular-season finale for the Panthers last season, became the first quarterback in league history to go 5-0 without throwing a pick.

Allen completed 20-of-32 passes for 227 yards and two TDs in a victory over the Tampa Bay Buccaneers in London. He has thrown seven touchdowns on the year. While he doesn't throw interceptions, he has lost four fumbles.

Three of Allen's victories have come on the road. A quarterback controversy could be looming, as Newton is reportedly not guaranteed to get the starting gig back when healthy.

Bridgewater, meanwhile, has thrown for seven TDs against just two picks for New Orleans. A one-time Pro Bowler who missed the entire 2016 season after tearing his ACL in training camp, Bridgewater revived his career with the Saints. He is a free agent this offseason and could find himself with plenty of suitors willing to make him a starter.

3. Kirk Cousins, Vikings' passing attack finding groove

For the second straight game, Kirk Cousins led his team to victory—and in the process—appeased a disgruntled star receiver. Last week, Cousins completed seven passes and a pair of TDs to Adam Thielen, who racked up a season-high 130 receiving yards against the Giants. Thielen, a two-time Pro Bowler, had complained before the contest about the offense's inability to throw the ball successfully.

Stefon Diggs, who skipped practice before the road tilt at New York due to frustration with his lack of involvement in the offense, was the centerpiece of the Minnesota Vikings' 38-20 thumping of the Philadelphia Eagles. Diggs collected seven receptions for 167 yards with a career-best three touchdowns.

Diggs was the subject of trade rumors the past two weeks, but his monster performance should quiet that chatter down immediately.

Cousins logged a four-touchdown afternoon, getting the scoring started with a 6-yard TD pass to Thielen on the opening drive, before linking up with Diggs for three scores over the next two quarters. Cousins has played tremendous the past two contests, throwing for a combined 639 yards with six touchdowns against one interception.

4. Russell Wilson emerges as MVP frontrunner

Seattle Seahawks QB Russell Wilson willed his team to a come-from-behind victory over the Cleveland Browns. The Seahawks fell behind 20-6 and trailed 28-25 in the fourth quarter, until Wilson drove his team down the field for a game-winning touchdown. While it was running back Chris Carson, who punched in the go-ahead score, Wilson was the driving force behind his club's comeback road win.

Wilson finished 23-of-33 for 299 yards with two passing TDs and a 117.6 passer rating. He ran for a touchdown as well, totaling 31 rushing yards. Wilson didn't commit a turnover and has yet to throw an interception this season.

Wilson is playing MVP-quality football in what is arguably the best stretch of his career.

By defeating host Cleveland, Seattle is 3-0 on the road for the first time since 1980.

5. San Francisco's defense looks elite

The 49ers' defense played incredible in their 20-7 win over Los Angeles Rams. The Rams went 0-for-13 on third and fourth down. Even worse, LA had just 165 yards of total offense, the fewest of the Sean McVay era.

San Francisco brought the pressure against the Rams, collecting four sacks. The 49ers also forced a fumble in what was their second straight defensive masterpiece.

The 49ers rank No. 2 in total defense and points allowed, behind only the Patriots in each category.

6. Jared Goff is imploding 

While the 49ers' ferocious defense was commendable, the struggles of Jared Goff might be the bigger story of Sunday's NFC West showdown. Goff signed a $134 million extension in the offseason—including an NFL-record $110 million guaranteed—following a Pro Bowl campaign last season which included a trip to the Super Bowl.

Not looking the part of a top-notch quarterback, Goff continues to turn the ball over often. In addition to throwing for a career-low 78 passing yards, Goff lost yet another fumble.

Goff has as many touchdowns (7) as interceptions, despite having Cooper Kupp, Robert Woods, Brandin Cooks and Todd Gurley at his disposal in the passing attack. The offensive line has had its major problems, so LA's woes don't fall all on Goff. But Goff is currently the weak link of the Rams, who have lost three in a row following a 3-0 start.