1. QBs streaks
Both Josh Allen and Patrick Mahomes come into Sunday's game streaking. Mahomes enters the AFC title game on an 11-game win streak (he did not play Week 17), while Allen brings an eight-game winning streak with him.
Combining their passing and rushing production, Allen and Mahomes were the only QBs to average 300-plus total yards per game and account for 40 or more total touchdowns this season.
The 2020 AFC Championship Game will be the first playoff game in NFL history between opposing starting QBs that averaged 300-plus total yards per game, and 40 or more total touchdowns as well as a passer rating of 100 or more in that regular season.
During Mahomes' win streak he has 26 TDs against five INTs for a 108.6 passer rating.
Allen on his winning streak has 19 TDs against three INTs for a 111.4 rating.
These two are the clear showpieces of this matchup, but they'll need their supporting casts to step up to assist in this one.
2. Bills 'D' up, Chiefs scoring down
As impressive as Mahomes' exploits have been the Chiefs point-scoring prowess has been curtailed of late. While Mahomes has averaged 33.5 points per game in his postseason career, Kansas City's close to the 2020 campaign has been a different story.
The Chiefs have scored 22 points or less in each of their last three games, counting their Divisional Playoff victory over Cleveland. Granted one of those games featured Chad Henne (Week 17), but there is no mistaking the stark contrast in their average margin of victory in the first half of the 2020 season to the second.
Kansas City won by an average of 15.6 points in their wins from Weeks 1-8. Since Week 9 their margin of victory is a mere four points. In fact, in Kansas City's last eight victories they've won all of them by six points or less.
The root of the problem has been the red zone. Since Week 12, the Chiefs rank 26th in red zone touchdown efficiency (45.8%). In 24 red zone possessions over that span they have just one more touchdown scored (11) than field goals (10). And those issues continued in the Divisional Playoff where they managed just two touchdowns on five trips to the red zone (40%).
Meanwhile Buffalo's defense has been on the ascent. The Bills defensive unit Kansas City faced in Week 6 was far from a finished product and did not have starters Matt Milano or Levi Wallace in the lineup.
Since Week 12, Buffalo's defense has shaved almost 10 points off their points allowed average (now 17.1). They've reduced their third down conversion rate by more than 11 percent (now at 35.1%) and the opponent passer rating has dropped more than 21 points (now 75).
The success of the Bills defense can be tied to the red zone. Buffalo has been the second-best defense in the red zone this postseason allowing just two touchdowns on eight possessions (25%).
The Bills defense also leads all playoff participants remaining allowing just 13.5 points per game.
3. Will big plays be there for Allen?
While much has been made of Buffalo's defensive approach in their first meeting with the Chiefs this season back in Week 6, which guarded against any big plays in the passing game, it's Kansas City's defense that has been among the best at eliminating big plays by the opposing offense.
Allen's downfield passing has strongly correlated to wins and losses for the Bills this season. Counting playoffs, Allen has 18 touchdowns, four interceptions and a 126.5 passer rating on downfield passes in wins and three touchdowns, five interceptions and a 55.2 passer rating on downfield passes in losses.
The Chiefs have allowed a 74.8 passer rating to opponents on downfield passes this season, including the playoffs, which is the fourth-lowest mark in the league and they've pulled down the most interceptions this season off deep passes with 13.
"They showed a couple different things on defense and stuff we probably weren't expecting," said Josh Allen of their Week 6 meeting with Kansas City. "I think we've gotten a lot better since that game. They can say the same thing and it's just two good teams that are going to go out there and compete and it's going to be a four quarter dogfight. We know that. We understand that."
But Kansas City's prevention of big plays could be compromised this week. Starting CB Bashaud Breeland has been slowed this week by a shoulder injury and a concussion. Fellow CB Rashad Fenton has also been slowed by a foot injury.
Chiefs DC Steve Spagnuolo blitzed Allen back in Week 6 at a rate of 52 percent and it proved effective with a steady diet of different coverage schemes.
But as the season wore on, Buffalo's quarterback improved against the blitz compiling the most passing yards against the blitz (1,568) and the fifth-most touchdowns (14). Allen also had John Brown playing on an injured knee in Week 6 as he did not have a single reception in the game.
Now healthy, Allen has his best deep threat available. His deep pass completion percentage jumps more than 15 percent when Brown is on the field (47.7%) than without him (32.3).
"We've got to do everything in our power to put our best foot forward and not make dumb mistakes and put the ball where it needs to be," Allen said. "If they go to their zone or if they play man we've got to win our matchups outside and get our run game established and play really good complementary football."
Add in the struggles of the Kansas City defense since Week 11 when they've allowed over 100 yards on downfield passes in seven of their last eight games and it appears there could be more opportunity than initially thought.
In six of the Chiefs last nine losses they've given up more big plays than they've had themselves. Buffalo is 10-0 this season when they've had the same or more big plays than their opponent.
4. A different defensive approach?
Buffalo's defensive game plan back in Week 6 made sense. Do not let the Chiefs beat you over the top with downfield passing plays that led to easy points. The Bills defense played deep coverage to keep everything in front of them for most of the game, never blitzed Patrick Mahomes and dared Kansas City to run the ball. The Chiefs did just that to the tune of 245 yards. But it was a one-score game with under 10 minutes to play in the game, which came close to achieving the aim of Buffalo's coaching staff. They just didn't get enough help from their offense.
So will the defensive game plan be different the second time around for Buffalo?
"Our plan is a lot different this week," said defensive captain Jordan Poyer. "I think when we first played them we definitely wanted to limit the explosives so we were playing two high safeties the whole games, inviting them to run the ball. So I think we'll be a little bit more aggressive, be able to show up in the run game but also be able to get back in there in the passing game."
Buffalo's defensive approach could also hinge on the mobility of Patrick Mahomes, who is dealing with a foot injury suffered in last week's game against the Browns. If he can't extend plays with his legs, it could prompt a more aggressive defensive plan.
Some other defenses this season that had success against the Chiefs did pressure Mahomes with varying degrees of effectiveness.
In Week 13, Denver blitzed Mahomes just over 29 percent of the time (12 total pass plays). While the Chiefs QB still threw for 318 yards and a touchdown, Kansas City's offense converted just three of their 10 third down opportunities, were 0-for-4 in the red zone and 0-for-3 in goal to go situations. The Chiefs still won 25-19, but were certainly slowed by the Broncos defensive plan.
In Week 16, Atlanta was far more aggressive. They blitzed more than 42 percent of the time, the second-highest rate against Kansas City this season. Mahomes completed just 55 percent of his passes with two touchdowns and an interception with a passer rating of 79.5. The Chiefs converted only five of their 13 third down chances and Mahomes INT was thrown in the end zone.
Kansas City won 17-14 after a chip shot field goal was missed by the Falcons in the waning seconds, which could've forced overtime. And Atlanta had the worst pass defense in the league.
But it proves there are different ways to at least slow the Chiefs offense down.
5. Unstoppable forces
Stefon Diggs and Travis Kelce finished first and second in the league in receiving yards and first at their positions in receptions this season for a reason. Both are unstoppable forces that are essentially unguardable against most any defense in the league.
Diggs has been especially effective against man coverage in his first season with the Bills. His 84 targets, 64 receptions and 919 receiving yards against man coverage all lead the league including playoffs.
Kansas City plays the highest rate of press coverage in the league (42% of snaps) and pressed Diggs 58 percent of the time in Week 6. Buffalo's top wideout responded with six receptions for 46 yards and a touchdown.
Diggs has turned things up since then. In his last nine games, counting playoffs, he has averaged just over 106 receiving yards per game, almost nine catches per game and has seven touchdowns.
Meanwhile Kelce has thrived against zone coverage. He leads the league in receiving yards against zone defenses (1,061 yards) is tied for the league lead in receiving touchdowns (5) and stands second in receptions (79).
Buffalo used defensive backs in matchups with Kelce almost exclusively in Week 6, assigning LB AJ Klein to Kelce on just one of his 22 routes. Tre'Davious White was most frequently assigned to Kelce in the first matchup (9 times).
The matchup assignments figure to be different Sunday as Matt Milano, who handles a myriad of coverage assignments, did not play in Week 6 due to a pectoral injury. He'll play Sunday and is a notable playmaker in the Bills defensive front. Milano has a 66.7 passer rating against in coverage this season.
If Buffalo can limit his yards after the catch it will go a long way in getting Kansas City's offense off the field.
6. Red zone edge
While Kansas City's red zone offense has been below their normal standard, their red zone defense has been poor all year long. The Chiefs had the worst red zone defense in the regular season giving up touchdowns at a rate of more than 76 percent (36-47).
That has continued in the postseason as they surrendered a touchdown on each of the Browns two red zone possessions in the Divisional Playoff.
Buffalo was a respectable 13th in the league in red zone offense in the regular season (62%) and has since raised that level of success to 75 percent in the playoffs against two very good defensive units in Indianapolis and Baltimore.
The Bills tied the Saints for the most red zone possessions in the league (68) and ranked fourth in the league with 42 red zone touchdowns.
Josh Allen has thrown 43 touchdowns and no interceptions in the red zone in his career along with another 24 red zone rushing touchdowns.
7. Running backs banged up
While the Bills lost Zack Moss for the season in the Wild Card Playoff versus Indianapolis, the Chiefs are a hobbled bunch at the position as well. Clyde Edwards-Helaire has missed the last five games with hip and ankle injuries. He's been limited in practice this week and is listed as questionable.
The Chiefs anticipate that they'll have Edwards-Helaire available to them in some capacity, but it certainly doesn't sound like the rookie tailback will be able to give them as much as he did in Week 6 when he rumbled for 161 yards.
Thinning the unit even more is midseason pickup Le'Veon Bell sustained a knee injury in practice on Thursday and is questionable for Sunday's game too.
That leaves the Chiefs with Darrel Williams as the most likely lead back with Edwards-Helaire presumably serving as a complementary piece in the offensive backfield.
Kansas City also has Darwin Thompson, but he's more of a third down scat back.