luckadjusted
NFL Week 9 · 2026

Week 15 2024 · December 15, 2024

Chiefs at Browns, Week 15 2024: who deserved to win?

The Chiefs beat the Browns 21–7, and the replays back it up: with the way both teams actually played, the Chiefs win 10 of 10.

Before kickoff the Chiefs were 63% favorites. The biggest swing (Q1, 13:46 left): the Browns fumbled and the Chiefs recovered, worth 8 points of win probability to the Chiefs.

Final

Kansas City Chiefs 21
Cleveland Browns 7

December 15, 2024 · FirstEnergy Stadium · Closing line: Chiefs −4.5

Luck index +2 Chiefs about even · −2 Browns

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 10, Browns win 0.

  1. 1 KC 50 CLE 10
  2. 2 KC 41 CLE 10
  3. 3 KC 27 CLE 0
  4. 4 KC 30 CLE 6
  5. 5 KC 32 CLE 12
  6. 6 KC 37 CLE 20
  7. 7 KC 31 CLE 17
  8. 8 KC 30 CLE 19
  9. 9 KC 13 CLE 6
  10. 10 KC 27 CLE 24

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

Chiefs win 98% of them, Browns 2%. The line is what actually happened: Chiefs by 14.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+82.8%
Chiefs by 9–1611.6%
Chiefs by 1–83.6%
Level after regulation0.4%
Browns by 1–81.4%
Browns by 9–160.1%
Browns by 17+0.1%

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 +1.3 points to the Browns: the final margin was Chiefs by 14, without the luck Chiefs by 15.3. Luck shares are the fitted ones (how much of each kind is luck).

Penalties: Chiefs 4 for 30 yards, Browns 6 for 45 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 half toward luck; pre-snap fouls, which repeat, don’t count. How calls are valued

WhenFlagWin probability for
Q1 10:06 Illegal Contact on the Chiefs (Joshua Williams), 5 yards +5% CLE +1.3 pts
Q1 7:53 Illegal Formation on the Browns (Mohamoud Diabate), 5 yards · pre-snap +1% KC +0.5 pts
Q2 14:08 Ineligible Downfield Kick on the Browns (Mohamoud Diabate), 5 yards +1% KC +0.5 pts
Q2 4:46 Defensive Offside on the Browns (Denzel Ward), 5 yards · pre-snap +1% KC +0.5 pts
Q3 3:01 Offensive Holding on the Browns (Pierre Strong), 10 yards 0% KC +0.8 pts
Q3 2:21 Face Mask on the Chiefs (Joshua Williams), 15 yards +3% CLE +1.5 pts
Q3 0:40 Intentional Grounding on the Browns (Jameis Winston), 15 yards +2% KC +0.8 pts
Q4 5:49 Illegal Formation on the Browns, 5 yards, wiping out the play · pre-snap +2% KC +1.5 pts
Q4 5:23 False Start on the Chiefs, 5 yards · pre-snap 0% CLE +0.6 pts
Q4 3:42 False Start on the Chiefs (Xavier Worthy), 5 yards · pre-snap 0% CLE +0.5 pts

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

When it happened

Browns’ chance of winning

As low as 0% and as high as 60%. 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 Browns were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:46 The Browns fumbled and the Chiefs recoveredFumble bounces · loose balls are close to 50/50 +8% KC CLE: Punt
2 Q1 10:06 Illegal Contact on the Chiefs (Joshua Williams), 5 yardsJudgment calls · 14 flags in 2025 snaps before, position avg 1 per 215 +5% CLE CLE: Punt
3 Q1 4:28 The Browns converted 3rd & 103rd & 4th downs · 23% expected +6% CLE CLE: Turnover
4 Q1 2:30 The Browns converted 3rd & 63rd & 4th downs · 32% expected +5% CLE CLE: Turnover
5 Q2 14:23 The Browns were stopped on 3rd & 53rd & 4th downs · 36% expected +4% KC CLE: Punt
6 Q2 13:20 The Chiefs were stopped on 3rd & 63rd & 4th downs · 42% expected +4% CLE KC: Punt
7 Q2 7:10 The Chiefs converted 3rd & 93rd & 4th downs · 34% expected +5% KC KC: Touchdown
8 Q2 0:24 H. Butker missed a 29-yard field goalKicks · 97% expected for him +5% CLE KC: Touchdown

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.

  • David Njoku (CLE TE), out · 0.8 pts
  • Jeremiah Owusu-Koramoah (CLE LB), out (IR) · 0.5 pts
  • Greg Newsome II (CLE CB), out (IR) · 0.5 pts
  • Cedric Tillman (CLE WR), out · 0.4 pts
  • Dustin Hopkins (CLE K), out · 0.3 pts
  • Spencer Shrader (KC K), out (IR) · 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 100% · Browns 0%

Final margin
Chiefs by 14
Luck in points
1.3 for the Browns
Luck-adjusted margin
Chiefs by 15.3
Replay with same day's form
Chiefs 98% · Browns 2% unchanged: why
How much of each is luck?

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

What counts

None by default: our tests measured no carryover after a lucky break. Slide it up to count a break for more than its own swing. 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 15 2024 games · Chiefs · Browns

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