luckadjusted

AFC Championship 2024 · January 26, 2025

Bills at Chiefs, AFC Championship 2024: who deserved to win?

The Chiefs beat the Bills 32–29, and it was no fluke: replayed with the way both teams actually played, the Chiefs win 9 of 10. The Bills had the bounces: fumble bounces alone were worth 27 points of win probability to the Bills.

Before kickoff the Chiefs were 54% favorites. The biggest swing (Q4, 2:00 left): the Bills were stopped on 4th & 5, worth 25 points of win probability to the Chiefs.

Final

Buffalo Bills 29
Kansas City Chiefs 32

January 26, 2025 · GEHA Field at Arrowhead Stadium · Closing line: Chiefs −1.5

Luck index +13 Chiefs about even · −13 Bills

Each team’s own plays from this game, resampled into new drives 4,000 times: with the way both teams actually played, how often does this performance win? How the replay works

Ten replays. Bills win 1, Chiefs win 9.

  1. 1 BUF 27 KC 20
  2. 2 BUF 24 KC 26
  3. 3 BUF 17 KC 21
  4. 4 BUF 13 KC 20
  5. 5 BUF 13 KC 22
  6. 6 BUF 17 KC 28
  7. 7 BUF 13 KC 27
  8. 8 BUF 7 KC 24
  9. 9 BUF 3 KC 24
  10. 10 BUF 10 KC 37

Three other ways to ask

Each answers a different question, so none of them replaces the replay above.

The closing betting line, turned into a probability. What everyone knew before the game.

The line plus what this game showed, weighted by how much one game can tell. It stays close to the line because one game says little.

Every kick, fumble bounce, drop, conversion and judgment call redrawn; everything else fixed. The narrowest view of luck.

How 4,000 replays ended

Bills win 13% of them, Chiefs 87%, counting the 1% still level after regulation as half each. The line is what actually happened: Chiefs by 3.

Show as a table
Final margin in the replaysShare of replays
Bills by 17+1.2%
Bills by 9–162.7%
Bills by 1–88.6%
Level after regulation1.4%
Chiefs by 1–819.3%
Chiefs by 9–1625.4%
Chiefs by 17+41.3%

Where the luck was

What the luck was worth

Every lucky and unlucky play, weighted by the moment it happened: its swing in win probability, added up by kind. A missed kick in a decided game counts for nothing; the same kick at the end of a tie game can be most of a win.

Swings add up across a game, so in one that went back and forth they can pass 100%. On the scoreboard the same luck was worth +3.8 points to the Bills: the final margin was Chiefs by 3, without the luck Chiefs by 6.8. Luck shares are the fitted ones (how much of each kind is luck).

The kicks

How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.

  • T. Bass, 53 yds made · 61% expected
  • H. Butker, 35 yds made · 92% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Bills 6 for 48 yards, Chiefs 5 for 21 yards

Every accepted flag, in order, and what it did to the helped team’s chance of winning at that moment, including any play it wiped out (points on the scoreboard in grey). A flag in a decided game is worth nothing; one at the turn of a close game can be worth most of a win. Judgment calls count toward luck, pre-snap fouls mostly don’t. How calls are valued

WhenFlagWin probability for
Q1 8:56 Illegal Formation on the Bills, 5 yards · pre-snap +2% KC +1.0 pts
Q1 2:28 Defensive Offside on the Bills (Ed Oliver), 5 yards, wiping out the play · pre-snap +6% KC +1.8 pts
Q2 14:22 Defensive Holding on the Chiefs (Nick Bolton), 5 yards +2% BUF +0.6 pts
Q2 4:41 Face Mask on the Bills (Kaiir Elam), 11 yards +4% KC +1.2 pts
Q2 2:00 Unnecessary Roughness on the Bills (Jordan Phillips), 8 yards +2% KC +0.4 pts
Q2 1:27 Defensive Pass Interference on the Chiefs (Jaylen Watson), 5 yards 0% BUF +0.2 pts
Q2 0:23 Defensive Offside on the Chiefs (Justin Reid), 1 yard · pre-snap 0% BUF +0.1 pts
Q3 13:42 Defensive Pass Interference on the Bills (Kaiir Elam), 4 yards +3% KC +0.6 pts
Q3 2:13 False Start on the Chiefs, 5 yards · pre-snap +2% BUF +0.8 pts
Q3 1:56 Illegal Use of Hands on the Chiefs (Charles Omenihu), 5 yards +3% BUF +0.8 pts
Q4 6:11 Face Mask on the Bills (Matt Milano), 15 yards +6% KC +1.8 pts

Bills penalties, every game · Chiefs penalties, every game · All teams, 2024

When it happened

Chiefs’ chance of winning

As low as 37% and as high as 100%. Numbers mark the biggest luck moments, listed below.

nflfastR’s in-game win probability. It ignores the betting line, so it starts near even. Shaded above the middle while the Chiefs were ahead in it, below while the Bills were.
#WhenWhat happenedWin probability forNext drive
1 Q2 10:53 The Bills converted 3rd & 133rd & 4th downs · 27% expected +12% BUF BUF: Touchdown
2 Q3 0:56 The Bills fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +10% BUF BUF: Turnover on downs
3 Q4 15:00 The Bills converted 4th & 13rd & 4th downs · 77% expectedThe Bills fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +14% BUF BUF: Turnover on downs
4 Q4 13:01 The Bills were stopped on 4th & 13rd & 4th downs · 77% expected +14% KC BUF: Touchdown
5 Q4 7:38 The Bills converted 3rd & 83rd & 4th downs · 35% expected +14% BUF BUF: Touchdown
6 Q4 6:20 The Bills converted 4th & 43rd & 4th downs · 40% expected +15% BUF BUF: Touchdown
7 Q4 3:37 H. Butker made 35-yard field goalKicks · 92% expected for him +10% KC KC: End of game
8 Q4 2:00 The Bills were stopped on 4th & 53rd & 4th downs · 44% expectedD. Kincaid dropped a catchable passDrops · 5 drops on 143 catchable balls before this +25% KC –

Missing players

Key players (usually on the field for half the snaps or more) who missed this game or part of it, valued by position and quality. The same players are missing in every replay, so this counts as luck in points only.

  • Taylor Rapp (BUF SS), out · 0.5 pts

Adjust the assumptions

Disagree with how much of a fumble bounce or a pass interference call is luck? Change it and the coin-flip replay reruns in your browser.

Only coin-flips re-rolled

Bills 11% · Chiefs 89%

Final margin
Chiefs by 3
Luck in points
3.8 for the Bills
Luck-adjusted margin
Chiefs by 6.8
Replay with same day's form
Bills 13% · Chiefs 87% unchanged: why
How much of each is luck?

0% treats it as skill, 100% as pure luck. The tick is our fit.

What counts

We tested momentum on 19,000 lucky breaks and found none, so it's off by default. Why

Flip a play

Force the other outcome, in this game and in every replay: a made kick becomes a miss, a stop becomes a conversion, a flag goes the other way.

About these numbers

Play-by-play and win probability from nflfastR via nflverse; kicks valued against each kicker’s own record; drops and interception-worthy throws from FTN charting; injuries from snap counts and injury reports.

Methodology and validation · All Conference championships 2024 games · Bills · Chiefs

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