Chad Henne was the unlikeliest of NFL playoff heroes last week. The Kansas City Chiefs’ backup quarterback had run for just 19 net yards since 2014. Yet on a critical late-game third-down against the Cleveland Browns, Henne somehow scrambled for 13 of the 14 yards he needed to convert. Then, in the middle of color commentator Tony Romo assuring the football-watching world that Henne would simply try to draw the Browns offside with a hard count, Henne executed a flawless psych-out play on 4th-and-short to seal a trip to the AFC Championship Game.
The Chiefs are the defending Super Bowl champions, the preseason Super Bowl favorite (by Vegas odds and the FiveThirtyEight predictions), the AFC’s No. 1 seed and current co-favorites to win Super Bowl LIV. But their season could have ended last week if they hadn’t gotten lucky.
The Chiefs were in trouble the moment starter Patrick Mahomes was knocked out of the game with a suspected concussion. After all, Mahomes’s greatness has been the driving force behind an offense that’s finished in the top three of Football Outsiders’ offensive Defense-adjusted Value Over Average (DVOA) for three seasons running. As pregame favorites, the Chiefs’ win probability in ESPN’s model never dipped below 77.2 percent — but hanging on to a 5-point lead with a backup quarterback in an elimination game felt like hanging from the edge of a cliff.
That close shave against the Browns seemed like a high-stakes version of their 17-14 comeback win over the lowly Atlanta Falcons in Week 16. And their 3-point win over the New Orleans Saints the week before. The eventual 5-11 Denver Broncos led the Chiefs for much of their Week 13 matchup, the Las Vegas Raiders made them sweat in Week 11,1 and they beat the Carolina Panthers by only 2 in Week 9.
Even though the Chiefs finished 14-2, they haven’t felt nearly as dominant as they did during last year’s 12-4 campaign. In fact, across the back half of their regular season, the Chiefs went 7-1 despite outscoring their opponents by only 10 points. When you’re winning that many games by an average of 1.25 points, you’re getting lucky.
As FiveThirtyEight’s Neil Paine wrote at the season’s halfway point, measuring point differential via Pythagorean expectation is one of the best ways we have to judge just how fortunate (or unfortunate) a football team has been. At that point, the undefeated Pittsburgh Steelers had won 2.3 more games than their point differential would indicate, making them the fourth-luckiest 8-0 team since 1960. “When a team wins more than the formula says it ‘should have,’” Paine wrote, “that usually means it won an unusual number of toss-up games, which may not be sustainable going forward.”
Using the same method, how lucky were the Chiefs in the last eight games of the regular season? The luckiest:
Since midseason, the Chiefs have had a lot of luck
NFL teams with the largest gaps between actual and expected record (based on the Pythagorean expectation*) over a season’s last eight games, since 1978
| Points | ||||||
|---|---|---|---|---|---|---|
| Year | Team | Record | Scored | Allowed | Pythag W. | Gap vs. Exp. |
| 2020 | Chiefs | 7-1 | 220 | 210 | 4.2 | +2.8 |
| 2018 | Cowboys | 7-1 | 185 | 173 | 4.3 | +2.7 |
| 1989 | Oilers | 5-3 | 154 | 214 | 2.5 | +2.5 |
| 2008 | Dolphins | 7-1 | 174 | 154 | 4.6 | +2.4 |
| 2006 | Chargers | 8-0 | 244 | 169 | 5.6 | +2.4 |
| 1999 | Colts | 7-1 | 200 | 171 | 4.7 | +2.3 |
| 1994 | Giants | 6-2 | 127 | 133 | 3.8 | +2.2 |
| 1996 | Jaguars | 6-2 | 174 | 182 | 3.8 | +2.2 |
| 2008 | Bengals | 4-3-1 | 100 | 147 | 2.3 | +2.2 |
| 2016 | Dolphins | 6-2 | 190 | 198 | 3.8 | +2.2 |
This year’s Chiefs outperformed their Pythagorean win total over the last eight games by more than any other team since the NFL moved to a 16-game schedule in 1978. Out of 1,241 teams that have played a full eight-game second-half schedule,2 none was as lucky as the Chiefs.
At the halfway mark, the Chiefs hadn’t been as fortunate as the Steelers — but with 1.3 more wins than expected, they had outperformed their Pythagorean expectation more than all but five other teams. After the luckiest stretch run of the modern era, they finished as the third-luckiest team ever to play a 16-game season:
The Chiefs’ full season was pretty lucky
NFL teams with the largest gaps between actual and expected record (based on the Pythagorean expectation*) over a regular season, since 1978
| Points | ||||||
|---|---|---|---|---|---|---|
| Year | Team | Record | Scored | Allowed | Pythag W. | Gap vs. Exp. |
| 1992 | Colts | 9-7 | 216 | 302 | 5.0 | +4.0 |
| 2012 | Colts | 11-5 | 357 | 387 | 7.2 | +3.8 |
| 2020 | Chiefs | 14-2 | 473 | 362 | 10.5 | +3.5 |
| 2004 | Steelers | 15-1 | 372 | 251 | 11.5 | +3.5 |
| 2019 | Packers | 13-3 | 376 | 313 | 9.7 | +3.3 |
| 2016 | Raiders | 12-4 | 416 | 385 | 8.7 | +3.3 |
| 2020 | Browns | 11-5 | 408 | 419 | 7.7 | +3.3 |
| 2009 | Colts | 14-2 | 416 | 307 | 10.8 | +3.2 |
| 1999 | Titans | 13-3 | 392 | 324 | 9.8 | +3.2 |
| 2011 | Packers | 15-1 | 560 | 359 | 11.9 | +3.1 |
Of course, the Chiefs haven’t just been lucky. Not only did they have the second-most effective offense in the NFL by DVOA this regular season, but they were the second-most consistent from week to week. They led the NFL in offensive yards and finished sixth in scoring offense.
The problem has been on the other side of the ball.
At first glance, the Chiefs’ defense wasn’t bad; they finished tied for 10th in points allowed and 16th in yards allowed. But they had the worst red-zone defense in the NFL according to Pro-Football-Reference.com, allowing touchdowns on a whopping 76.6 percent of opponent drives that reached the red zone. The Chiefs finished 22nd in defensive DVOA and 24th in weighted DVOA — meaning they were less effective later in the season.
Chiefs head coach Andy Reid and offensive coordinator Eric Bieniemy seem to know this. Though their offense was tied for the fourth-fewest number of drives in the league, they ran more plays per drive and gained more yards per drive than any other team. Despite their reputation as a high-flying, high-scoring offense built around Mahomes’s big arm, the Chiefs were tied for the third-longest average time of possession per drive.
This explains the sky-high offensive DVOA paired with relatively close, low-scoring games: The Chiefs use their consistency and skill on offense to keep their defense off the field. Of course, by letting underdog opponents hang around, they also risk getting beat.
The Steelers fell back to Earth in the second half of the season; they lost four of their last five regular-season games and were bounced out of the playoffs in the first round by the Browns. The Chiefs managed to avoid getting upset by that same Browns team — but they’ll likely need all their skill and luck to repeat as both AFC and Super Bowl champions.
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