Analytics Recap: Kansas City Chiefs Defeat Buffalo Bills 38-24 in AFC Championship Game

What do the advanced metrics have to say about the Kansas City Chiefs' 38-24 win over the Buffalo Bills in the AFC Championship Game to advance to Super Bowl LV?

The Kansas City Chiefs are AFC Champions for the second consecutive year after defeating the Buffalo Bills in the AFC Championship Game by a score of 38-24. Patrick Mahomes had an incredible performance in this game, throwing for 325 yards and three touchdowns with no interceptions, while fellow second-team All-Pro Josh Allen threw for 287 yards and two touchdowns while running for 88 yards, but Allen threw a back-breaking interception in the red zone in the fourth quarter while it was a two-score game.

The Chiefs will play their second consecutive Super Bowl, this time heading to Tampa Bay to play the Tampa Bay Buccaneers on February 7 for Super Bowl LV. This will be the ultimate moment of Mahomes' career, as he will have a chance to defeat Tom Brady, the six-time Super Bowl champion and the only quarterback to hand him a postseason loss to this point in his career.

Here are the advanced numbers from the Chiefs' win over the Bills from Ben Baldwin's rbsdm.com.

EPA = Expected Points Added, SR = Success Rate, 1st% = First Down Rate

The Chiefs offense was completely unstoppable in this one, finishing with a positive EPA in all types of plays, all passes, all runs, early-down passes, early-down runs, late-down passes and late-down runs. The passing game was sensational on all levels, getting over half of an expected point added to their tally on every pass, both for early downs and late downs. For the Bills, they were quite stagnant on offense with their passing game falling flat, thanks in part to the coaching of Steve Spagnuolo and Josh Allen playing worse against the blitz than he usually does.

Travis Kelce and Tyreek Hill had unbelievable performances in this one, with Kelce finishing with 0.78 EPA per play, 11.7 EPA and an 80% success rate over 15 plays and Hill finishing with 0.99 EPA per play, 10.9 EPA and an 82% success rate over 11 plays. Two other players who were really effective on offense were Mecole Hardman, who had 0.84 EPA per play, 4.2 EPA and an 80% first down rate over his five offensive plays, and Darrel Williams, who had 0.31 EPA per play, 5.4 EPA and a 50% first down rate over 14 plays. Unfortunately, Clyde Edwards-Helaire, who played his first game since Week 15, did not produce much at all, finishing with -0.54 EPA per play, -4.3 EPA and just two "successful" plays out of his eight plays in the game.

For the Bills, they had a few players put up average production, with Isaiah McKenzie getting 4.8 EPA, Dawson Knox getting 4.1 EPA, Cole Beasley getting 3.0 EPA and Stefon Diggs getting 2.8 EPA, but no one added a large amount of production in the game. John Brown also added 2.6 EPA on four of his five plays, but the fifth was a back-breaking interception from Josh Allen that came thanks to a great pass breakup by Bashaud Breeland. It was also a rough day for Devin Singletary, who had -2.9 EPA and two "successful" plays on nine plays for the Bills.

aDoT = Average Depth of Target, CMP% = Completion Percentage, xCMP% = Expected Completion Percentage, CPOE = Completion Percentage Over Expectation (Completion Percentage minus Expected Completion Percentage), xQBR = Expected Result for ESPN's Quarterback Rating metric

The performance put on by the combination of Patrick Mahomes, Andy Reid and Eric Bieniemy to make the Chiefs offense click was simply spectacular. Mahomes had a 0.57 EPA per play, which is 96th percentile and his highest since Week 8, and a 7.2 CPOE, despite having just a 5.5-yard average depth of target (9th percentile) and having zero completions of 20+ air yards. This was a magical showing with consistent good, short throws, and as a result, he received an 87.8 xQBR and a 91.9 grade from Pro Football Focus (PFF).

Josh Allen was completely off in this game; it was an uncharacteristically poor showing to cap off an excellent season for the young quarterback. He finished the game with -0.01 EPA per play, -0.4 Total EPA, 7.9 aDoT and -2.1 CPOE, all of which were below the 50th percentile. Allen had a truly incredible season, but his postseason certainly left much to be desired. 

The biggest play of the game came early on with Mecole Hardman's brutal muffed punt in the first quarter while trailing 3-0, setting the Bills up at the three-yard-line. This play was worth 7.0 EPA. The Bills' second-biggest play, and the fourth-biggest play of the whole game, was another special teams error for the Chiefs, as the Bills recovered an onside kick in the fourth quarter after scoring a touchdown. That play was worth -3.3 EPA for the Chiefs. The top two plays for the Chiefs were the Josh Allen fourth-quarter red-zone interception to Rashad Fenton, which was worth -6.2 EPA for the Bills, and Patrick Mahomes' 71-yard pass to Tyreek Hill to get to the Bills' four-yard-line, which was worth 5.2 EPA. Hardman's 50-yard run was the sixth-biggest play, worth 3.2 EPA, and Mahomes' third-and-goal fourth-quarter touchdown to Travis Kelce was the eighth-biggest play, worth 2.7 EPA.

Moving on to the win probability chart, the Chiefs had the win probability for about three-quarters of the game. They started the game with a 57.9% win probability advantage, but the Mecole Hardman fumble gave the Bills a huge jump in the mid-first quarter, giving them a 66.8% win probability. They finished the quarter with a 57.2% win probability, but that was short-lived with the Chiefs really turning it on soon after. At halftime, the Chiefs had an 85.5% win probability advantage, as they led 21-12. Their win probability continued to increase in the third quarter, hitting a high of 96.1% with 2:40 left in the third. Their win probability went in excess of 98% with 13:11 remaining and hit 100% after the Chiefs scored a touchdown to increase their lead to 38-17 with 7:41 remaining. 

For NFL Team Tiers by Offensive and Defensive EPA per play, the Kansas City Chiefs have taken the top spot in Offensive EPA with a 10-90% win probability, having an incredible 0.259 EPA per play this season with the Packers just trailing them with 0.248 EPA per play to finish the season. For this postseason, the Chiefs are also eighth in Defensive EPA allowed per play with 0.039, sixth in Defensive EPA allowed per dropback -0.021 and first in passing success rate with 37.5%.

Entering Super Bowl LV, the Buccaneers are currently fifth in Offensive EPA per play with 0.165 and seventh in Defensive EPA with 0.014. However, something to keep an eye on, as a Chiefs fan, is the Buccaneers' 0.092 Defensive EPA allowed per dropback, which ranks 14th.

For early-down passing rate, the Chiefs remain just barely in third place with a 62.9% rate, being 0.4% behind the Bills for first and 0.1% behind the Texans for second. For early-down EPA, the Chiefs are first in EPA per rush with 0.088 EPA per play and third in EPA per dropback with 0.302 EPA per play, trailing just the Titans and Packers.

Meanwhile, the Buccaneers rank ninth in early-down passing rate with a 55.6% rate, 12th in early-down EPA per dropback with 0.176 EPA per play and 12th in early-down EPA per rush with -0.054 EPA per play. 

For the first 20 weeks of the NFL season, Patrick Mahomes remains second in EPA+CPOE composite score (0.196) with a 0.361 EPA per play (second) and 3.8 CPOE (seventh). Ahead of him is Aaron Rodgers with a 0.224 EPA+CPOE composite score, 0.418 EPA per play and 5.9 CPOE (second), and just behind him is Josh Allen with a 0.181 EPA+CPOE composite score, 0.282 EPA per play (fifth) and 5.6 CPOE (fourth). The other Super Bowl quarterback, Tom Brady, ranks fifth in EPA+CPOE composite score (0.168), fourth in EPA per play (0.302) and 14th in CPOE (2.0). 

For the entire 2020-21 NFL postseason, Patrick Mahomes is the runaway best quarterback at this point in time. Mahomes' postseason EPA+CPOE composite score stands at an incredible 0.263 with a 0.495 EPA per play and 8.9 CPOE, all of which rank first in the postseason. Trailing Mahomes is Baker Mayfield with a 0.200 EPA+CPOE composite score, Aaron Rodgers with a 0.138 EPA+CPOE composite score, Philip Rivers with a 0.130 EPA+CPOE composite score and Tom Brady with a 0.119 EPA+CPOE composite score.

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