What makes Patrick Mahomes and Josh Allen so hard to stop?

Josh Allen and Patrick Mahomes are two of the most productive -- and unique -- quarterbacks in the NFL. ESPN

Stopping either Patrick Mahomes or Josh Allen in the final moments of the 2021 AFC divisional game between the Kansas City Chiefs and Buffalo Bills didn't seem possible. Two of the NFL's best quarterbacks exchanged blow after blow at Arrowhead Stadium.

Led by their quarterbacks, the teams combined for 25 points in the final two minutes of the fourth quarter, the second most in any game in the Super Bowl era. The game was the first in NFL history to feature both quarterbacks throwing for at least 300 yards, three touchdowns and no interceptions and also running for at least 50 rushing yards. It served as a showcase for two of the NFL's most unique and productive players at the position.

While the Chiefs would go on to another AFC Championship Game with a 42-36 victory in overtime, the dominance of the two quarterbacks and the success the offenses enjoyed will be remembered from that matchup between quarterbacks who have led the NFL in combined passing and rushing touchdowns since 2019.

"One of the biggest challenges is just ability. They have the ability to go left or right, see down the field and make throws that not many people in the league can make," longtime New England Patriots defensive back Devin McCourty said. "I think the second part of that is that they're both mobile enough to really hurt you. We saw that when they played against each other. It wasn't fun as a defensive player [to watch], but it was also cool to see their greatness show in the back and forth because it was those two guys making plays."

The current MVP favorites, per Caesars Sportsbook -- Allen +200 and Mahomes +450 -- will meet for the fifth time Sunday (4:25 p.m. ET, CBS). With the Bills and Chiefs leading the NFL in several offensive categories, the outcome of the game might again come down to which defense can make a stop.

However the game plays out Sunday, it will be a must-watch matchup between two quarterbacks who have been among the toughest for opposing defenses to solve. -- Alaina Getzenberg

MAHOMES HAS COMPLETED many unconventional passes in his four-plus seasons as an NFL starting quarterback, whether they be of the no-look, sidearmed or even left-handed variety.

He added to his collection in a recent Sunday night game against the Tampa Bay Buccaneers. After being chased from the pocket and scrambling behind the line of scrimmage for 39.4 yards, Mahomes did a 360 spin to avoid a defender before flipping a 2-yard touchdown pass to running back Clyde Edwards-Helaire.

More than anything, what sets Mahomes apart is his ability to quickly adapt to changing circumstances and make a play when seemingly none is there.

"The NFL hasn't seen anything like Mahomes, I promise you that,'' Chiefs tight end Travis Kelce said after the game. "You saw it today. He's the Houdini of our era. The guy just finds ways to make plays throughout the game -- big-time third downs, big-time goal-line plays, just willing our team to the end zone, willing our team to win. That's our ultimate leader, man."

Kelce would undoubtedly get agreement from the opposing teams Mahomes has most thrived against. One is the Las Vegas Raiders. After a sparkling come-from-behind performance in a 30-29 Chiefs win on Monday night, Mahomes is 8-1 against the Raiders with 26 touchdowns and three interceptions.

"The thing about Mahomes is obviously he's very, very good at when things don't go right scheme-wise, when the play breaks down, he's obviously someone who can adapt,'' Raiders defensive lineman Clelin Ferrell said. "That's probably the hardest thing for a rusher, because when you know where a quarterback's going to be ... it makes it a lot easier to know how you're going to rush him. But Pat Mahomes, it may be a play where he's backing out, he's 20 feet deep, and he's throwing it off his back foot.

"It's just being wary, knowing how to rush him, knowing when you can take chances, knowing when not to. Regardless of all that, we've got to be ready for him to run all day. Because he's really good at that, too, when the play breaks down. Don't get me wrong, I don't want to say [he's] unconventional. He knows he has a plan when he goes out there. I just feel he's really good at adapting.''

Mahomes is 3-1 against the Bills, including 2-0 in the playoffs, heading into Sunday's game at Arrowhead Stadium. Mahomes has a QBR of 84.2 against Buffalo.

"You think you've got things covered up, and then he starts moving around, and it becomes backyard football, and guys are scrambling and trying to get into position to make plays,'' Bills defensive coordinator Leslie Frazier said. "He's just a terrific athlete who can make throws from anywhere at any angle. There really is no defense for that. You've just got to hold on and hope you can make some plays along the way. But he's going to make some plays, getting out of the pocket, running for first downs, making weird throws off balance."

Blitzing and pressuring Mahomes generally hasn't been a good strategy for opposing defenses either. He is first since becoming a starter in 2018 in QBR when blitzed (91) and first when pressured (64).

Confusing him with coverages has been more effective. In the first half of last year's AFC Championship Game against the Cincinnati Bengals, Mahomes threw for 220 yards and three touchdowns. The Bengals then changed tactics, going almost exclusively with a three-player rush and dropping eight into coverage.

In the second half and overtime, Mahomes threw for 55 yards with two interceptions.

"It was forcing him to hold on to the ball a little bit, but keeping him in the pocket and not allowing him to buy extra time or the receivers to get away from coverage,'' McCourty said. "I thought it was very interesting some of the 3-man rush stuff they did. It sounds good, but you still need to create some kind of pressure with it.''

In Kansas City, Kelce isn't the only Chief to marvel at Mahomes' play. Coach Andy Reid does, too. He said he reminds his coaches to appreciate the moment each time Mahomes makes one of his special plays.

Maybe the only one who isn't impressed is Mahomes himself. To him, he's just doing what he does.

"I just try to win,'' Mahomes said after the Tampa Bay game. "At the end of the day that's what I try to do. It's not like I'm planning these things where I'm throwing sidearm or whatever it is, spinning, running around. I always say I'm a competitor, and I'm going to find whatever way I can do to make our team have success.

"Today was a spin and a little, I don't know, a basketball shot that ended up a touchdown." -- Adam Teicher

ALLEN STARTED THE Bills' 38-3 dismantling of the Pittsburgh Steelers on Sunday with a bang. On the Bills' third play, from their 2-yard line, Allen fired 38 yards downfield into a strong wind. Wide receiver Gabe Davis caught the pass mid-stride and raced into the end zone for the 98-yard score.

Allen didn't let up from there. In a three-minute span in the second quarter, he added three more touchdown passes before finishing the first half with 348 passing yards and four TDs against one interception. He finished the game with 424 yards, completing 20 of 31 passes, while also leading the Bills in rushing with 42 yards on five carries.

"Josh Allen is a creature. He's a beast," Bills linebacker Von Miller said. "He can make every throw on the football field. He can run the ball. He's big, he's strong. The aspect that I love about him the most is his ability to get guys to play at a level that they wouldn't normally play at. ... It's Josh Allen's ability to make these guys feel like superheroes."

Allen, 26, is 1-3 against the Chiefs and Patrick Mahomes all time, but it's not reflective of his play overall in those games, which includes 11 passing touchdowns to two interceptions and one rushing touchdown.

After steadily improving in his first two NFL seasons, Allen has since emerged as a top quarterback in the league over the past three years. His career-best season to date came in 2020, when his completion percentage jumped from 58.8% the year prior to 69.2%. His touchdown percentage improved from 4.3% to 6.5%.

"[Allen] plays smart. He makes you make sense. He's going to take his chances when he can, but he's not going to force the ball," Bills wide receiver Stefon Diggs said.

Extending plays has become one of Allen's specialties, and much of that comes from his improvement throwing outside the pocket. After throwing five touchdowns to seven interceptions and posting a 12.1 QBR on such throws in his first two seasons, Allen has been a different player from 2020 on.

Allen's QBR on throws outside of the pocket since 2020 is 70.9, and he has thrown 22 touchdowns to just two interceptions.

"Usually when you're playing a guy that can run, it's look downfield, look at the rush, then run," McCourty said of the defensive challenge. "When you play these guys who are able to be pocket passers but are also able to escape the pocket and throw or run, it presents a very tough challenge. I think how you slow them down -- you have to create some confusion."

Indianapolis Colts head coach Frank Reich said he's gained a lot of respect for how much Allen has grown as a player.

"I just think when you start looking at the particular skills of playing quarterback, you know, I saw it coming out like his first year, I thought he was great," Reich said. "But I thought his accuracy needed to be improved. And I think he's done a phenomenal job at that. I mean, he's really turned into not just a great athlete and a great playmaker, but I think he's turned into an accurate passer. I think he's worked at it."

Allen is also unique because of his size -- 6-foot-5, 237 pounds -- which makes him hard to bring down when the ball is in his hands, which it often is.

On the winning drive against the Baltimore Ravens in Week 4, Allen appeared set to take a sack for a loss of about 10 yards with linebacker Odafe Oweh closing in on him. Instead, he spun away, ran to his left and found rookie wide receiver Khalil Shakir downfield near the sideline.

"The biggest thing I think is just tackling when you get to him, because he's such a tough tackle. He's a D-end body type," Ravens defensive tackle Calais Campbell said. "He's pretty much the same size as Odafe, and he's strong and athletic, and he can make every throw on the move. So, he's a tough opponent. I think the biggest thing is just when you get to him, you have to get him down."

Campbell added: "I've seen him run over D-linemen, which is rare for a quarterback; I mean, it's rare for anybody with the ball in their hands, but especially a quarterback. So, I have the utmost respect for him. I know, for us to stop him, we have to bring our 'A' game. It's good quality football."

One of the major recent critiques of the Bills' offense has been that it relies too much on Allen and not enough is done to involve the running game. Allen is the Bills' leading rusher (35 carries, 225 yards and two touchdowns), and he has accounted for 16 of the Bills' 17 offensive touchdowns this season.

"[Allen's] an elite passer, he's an elite runner or creator. It's challenging. It's simple mathematics," Pittsburgh Steelers coach Mike Tomlin said. "They've got some receivers like Diggs that require attention that could mean two people, whether zone or man schematically. Anytime you're facing a quarterback like Josh, oftentimes it means five rushers. So, do the math. When you've got that type of talent on the perimeter, when you've got that type of talent in the pocket at quarterback, it makes defense challenging." -- Getzenberg