luckadjusted

Week 15 2024 · December 15, 2024

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

The Chiefs beat the Browns 21–7, and it was no fluke: replayed with the way both teams actually played, the Chiefs win 10 of 10. The Browns had the bounces: kicks alone were worth 3.5 points to the Browns.

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 46 CLE 6
  2. 2 KC 39 CLE 6
  3. 3 KC 42 CLE 14
  4. 4 KC 26 CLE 3
  5. 5 KC 30 CLE 10
  6. 6 KC 23 CLE 6
  7. 7 KC 29 CLE 14
  8. 8 KC 22 CLE 10
  9. 9 KC 27 CLE 20
  10. 10 KC 17 CLE 13

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+83.0%
Chiefs by 9–1611.6%
Chiefs by 1–83.5%
Level after regulation0.4%
Browns by 1–81.3%
Browns by 9–160.3%
Browns by 17+0.1%

Where the luck was

Take the luck out

The final margin was Chiefs by 14. Remove the luck, one kind at a time, and it becomes Chiefs by 15.5.

Each row takes one kind of luck out of the margin. Color shows which team it helped. Luck shares are the fitted ones (how much of each component is luck).

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 · 22% expected +6% CLE CLE: Turnover
4 Q1 2:30 The Browns converted 3rd & 63rd & 4th downs · 31% expected +5% CLE CLE: Turnover
5 Q2 14:23 The Browns were stopped on 3rd & 53rd & 4th downs · 34% expected +5% KC CLE: Punt
6 Q2 7:10 The Chiefs converted 3rd & 93rd & 4th downs · 32% expected +5% KC KC: Touchdown
7 Q2 0:24 H. Butker missed 29-yard field goalKicks · 97% expected for him +5% CLE KC: Touchdown
8 Q3 0:40 The Browns were stopped on 3rd & 153rd & 4th downs · 16% expectedIntentional Grounding on the Browns (Jameis Winston), 15 yardsJudgment calls · 9 flags in 2282 snaps before, position avg 1 per 658 +4% KC CLE: Punt

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
1.5 for the Browns
Luck-adjusted margin
Chiefs by 15.5
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

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 15 2024 games · Chiefs · Browns

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