The 2021 NFL season is quickly barreling towards a close, making this a great time to highlight some of the campaign's biggest surprises.

Some of these unexpected revelations involve rebuilding teams making a sudden push into contending status.

Others include young players either making an early leap to the top of their craft or contributing more than projected as rookies.

One of the year's shocking moments even involved a player being cut after the trade deadline before landing with an NFC contender.

With that in mind, here's a look at all the biggest surprises of the season thus far.

All stats and records taken on Saturday, December 4. 

Arizona Cardinals Rise Up

After narrowly missing the playoffs last season, the Cardinals seemed poised for further improvement in 2021. Few would have predicted the team would boast the league's best record going into Week 13.
Arizona started the year on a 7-0 run and is still 9-2 with less than a third of the season left to play.

The offense has been potent thanks to Kyler Murray making a leap in his third year. The quarterback has completed a league-best 72.7 percent of his passes for 2,276 yards and 17 touchdowns. He's also added 147 yards and three scores on the ground.

The Cardinals boast a deep receiving corps, with DeAndre Hopkins, A.J. Green, Christian Kirk and rookie Rondale Moore all playing a role. Each has caught at least 34 passes for 400 yards and a score this season.

While coach Kliff Kingsbury's high-flying Air Raid attack gets much of the credit—Arizona does rank in the top-10 for total offense and is a top-five scoring unit—the defense has been a key reason this club is still in a position to earn the NFC's playoff bye.

Arizona ranks in the top-five for both yards allowed and points against in 2021, a massive improvement from last year when the team finished outside the top-10 in both categories. This stingy defense has allowed the Cardinals to overcome injuries to key offensive players, such as Murray and Hopkins, over the last month.

The Cardinals have a tough stretch coming up—they'll face off with the Rams, Colts, Cowboys and Seahawks over the final six weeks—but this team has already proven its contending status after one of the most surprising starts to the season.

If Arizona gets healthy come playoff time, it will be a force to be reckoned with.


Mac Jones Becomes New England's Franchise QB

Even after the Patriots drafted Alabama quarterback Mac Jones with the No. 15 pick, Bill Belichick spent much of the offseason intimating that Cam Newton would remain New England's starter in 2021.

That appeared to be the team's plan until right before the regular season began. That's when the Pats made the shocking decision to cut Newton, opening the door for Jones to take over as the Week 1 starter.
It's a decision the Patriots have not regretted.