luckadjusted

Week 9 2025 · November 2, 2025

Chiefs at Bills, Week 9 2025: who deserved to win?

The Bills beat the Chiefs 28–21, and it was no fluke: replayed with the way both teams actually played, the Bills win 9 of 10.

An off day for the Chiefs: their offense and defense both played far below their usual level. In a fresh game against the Bills they would win 49% of the time; with this day’s form, 13%. The numbers

Before kickoff the Chiefs were 57% favorites. The biggest swing (Q4, 4:27 left): the Chiefs threw an interception-worthy pass, and it was picked, worth 16 points of win probability to the Bills.

Final

Kansas City Chiefs 21
Buffalo Bills 28

November 2, 2025 · New Era Field · Closing line: Chiefs −2.5

Luck index +13 Bills about even · −13 Chiefs

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. Chiefs win 1, Bills win 9.

  1. 1 KC 20 BUF 14
  2. 2 KC 20 BUF 22
  3. 3 KC 16 BUF 20
  4. 4 KC 20 BUF 27
  5. 5 KC 10 BUF 19
  6. 6 KC 23 BUF 34
  7. 7 KC 13 BUF 27
  8. 8 KC 30 BUF 47
  9. 9 KC 10 BUF 33
  10. 10 KC 14 BUF 45

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.

An off day for the Chiefs

Their offense and defense both played far below their usual level. In a fresh game against the Bills they would win 49% of the time; with this day’s form, 13%.

36 points apart for the Chiefs: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Chiefs offenseEPA per play gained −0.10 +0.17 worse by 0.27
Chiefs defenseEPA per play allowed +0.24 +0.09 worse by 0.15
Bills offenseEPA per play gained +0.24 +0.19 better by 0.05
Bills defenseEPA per play allowed −0.10 +0.13 better by 0.24

EPA (expected points added) per play on competitive snaps, turnovers left out because they are valued as luck. Usual level: the team’s earlier games this season plus half of last season, pulled toward the league average. One team’s defense and the other team’s offense are the same snaps, so one game can’t fully say whose day it was; it shows how far this one was from both teams’ norms.

How 4,000 replays ended

Chiefs win 13% of them, Bills 87%, counting the 2% still level after regulation as half each. The line is what actually happened: Bills by 7.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+0.7%
Chiefs by 9–162.6%
Chiefs by 1–88.5%
Level after regulation1.7%
Bills by 1–820.7%
Bills by 9–1624.5%
Bills 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 +6.4 points to the Chiefs: the final margin was Bills by 7, without the luck Bills by 13.3. 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.

  • H. Butker, 46 yds made · 82% expected
  • H. Butker, 19 yds made · 100% expected
  • M. Prater, 52 yds missed · 71% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Chiefs 3 for 25 yards, Bills 4 for 40 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 15:00 Offensive Holding on the Bills (Dorian Williams), 10 yards +1% KC +0.8 pts
Q1 14:14 Defensive Pass Interference on the Chiefs (Jaylen Watson), 5 yards +1% BUF +1.0 pts
Q1 2:17 Defensive Holding on the Bills (Cole Bishop), 5 yards 0% KC +0.3 pts
Q2 12:57 Face Mask on the Bills (Ty Johnson), 15 yards +2% KC +2.5 pts
Q2 8:06 Offensive Holding on the Bills (Dawson Knox), 10 yards, wiping out the play +8% KC +2.0 pts
Q3 6:27 Intentional Grounding on the Chiefs (Patrick Mahomes), 10 yards +2% BUF +1.0 pts
Q4 6:05 Offensive Holding on the Chiefs, 10 yards +4% BUF +1.5 pts

Chiefs penalties, every game · Bills penalties, every game · All teams, 2025

When it happened

Bills’ chance of winning

As low as 40% 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 Bills were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q1 8:05 The Bills converted 3rd & 83rd & 4th downs · 34% expected +8% BUF BUF: Touchdown
2 Q2 8:06 Offensive Holding on the Bills (Dawson Knox), 10 yards, wiping out the playJudgment calls · 16 flags in 4985 snaps before, position avg 1 per 278 +8% KC KC: Turnover on downs
3 Q2 4:15 The Chiefs were stopped on 4th & 33rd & 4th downs · 54% expected +9% BUF KC: Field goal
4 Q3 7:53 The Chiefs converted 3rd & 93rd & 4th downs · 31% expected +7% KC KC: Punt
5 Q4 14:20 The Chiefs converted 4th & 173rd & 4th downs · 21% expected +6% KC KC: Touchdown
6 Q4 11:34 The Chiefs converted 4th & 13rd & 4th downs · 68% expected +6% KC KC: Touchdown
7 Q4 4:27 The Chiefs were stopped on 3rd & 113rd & 4th downs · 28% expectedThe Chiefs threw an interception-worthy pass, and it was pickedInterceptions · 50% expected to stay out of the defense's hands +16% BUF KC: End of game
8 Q4 0:03 The Chiefs were stopped on 3rd & 103rd & 4th downs · 30% expected +8% BUF –

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.

  • Taron Johnson (BUF CB), out · 0.6 pts
  • Taylor Rapp (BUF S), out (IR) · 0.5 pts
  • Ed Oliver (BUF DT), out (IR) · 0.5 pts
  • DaQuan Jones (BUF DT), out · 0.4 pts
  • Shaq Thompson (BUF LB), out · 0.2 pts
  • Cameron Johnston (BUF P), out (IR) · 0.2 pts
  • T.J. Sanders (BUF DT), out (IR) · 0.1 pts
  • Josh Simmons (KC T), out · 0.7 pts
  • Isiah Pacheco (KC RB), out · 0.3 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

Chiefs 2% · Bills 98%

Final margin
Bills by 7
Luck in points
6.4 for the Chiefs
Luck-adjusted margin
Bills by 13.4
Replay with same day's form
Chiefs 13% · Bills 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 Week 9 2025 games · Chiefs · Bills

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