luckadjusted
NFL Week 9 · 2026

Week 8 2023 · October 29, 2023

Chiefs at Broncos, Week 8 2023: who deserved to win?

The Broncos beat the Chiefs 24–9, but the replays call it close to a coin flip: with the way both teams played, the Broncos win 5 of 10. Luck ran their way: fumble bounces alone were worth 14 points of win probability to the Broncos.

Before kickoff the Chiefs were 70% favorites.

Final

Kansas City Chiefs 9
Denver Broncos 24

October 29, 2023 · Empower Field at Mile High · Closing line: Chiefs −7

Luck index +50 Broncos lucky · −50 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 5, Broncos win 5.

  1. 1 KC 44 DEN 24
  2. 2 KC 31 DEN 20
  3. 3 KC 28 DEN 21
  4. 4 KC 17 DEN 13
  5. 5 KC 20 DEN 19
  6. 6 KC 34 DEN 37
  7. 7 KC 17 DEN 24
  8. 8 KC 24 DEN 35
  9. 9 KC 17 DEN 34
  10. 10 KC 7 DEN 33

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 50% of them, Broncos 50%, counting the 6% still level after regulation as half each. The line is what actually happened: Broncos by 15.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+10.7%
Chiefs by 9–1614.4%
Chiefs by 1–822.1%
Level after regulation5.6%
Broncos by 1–822.0%
Broncos by 9–1614.2%
Broncos by 17+11.0%

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 +0.5 points to the Broncos: the final margin was Broncos by 15, without the luck Broncos by 14.5. 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, 23 yds made · 99% expected
  • H. Butker, 34 yds made · 94% expected
  • H. Butker, 56 yds made · 62% expected
  • W. Lutz, 38 yds blocked · 87% expected
  • W. Lutz, 28 yds made · 95% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Chiefs 5 for 38 yards, Broncos 6 for 35 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 1:08 Defensive Offside on the Chiefs (Charles Omenihu), 5 yards, wiping out the play · pre-snap 0% KC +0.2 pts
Q1 0:40 Offensive Pass Interference on the Broncos (Courtland Sutton), 10 yards +2% KC +1.1 pts
Q2 13:35 Defensive Holding on the Broncos (Josey Jewell), 5 yards, wiping out the play +3% KC +1.0 pts
Q2 1:41 Defensive Holding on the Broncos (Patrick Surtain II), 5 yards +1% KC +0.4 pts
Q3 10:51 Defensive Holding on the Chiefs (L'Jarius Sneed), 5 yards, wiping out the play +5% DEN +1.6 pts
Q3 9:04 Illegal Formation on the Broncos, 5 yards · pre-snap +1% KC +0.9 pts
Q3 5:20 Defensive Holding on the Broncos (Fabian Moreau), 5 yards, wiping out the play +6% KC +1.7 pts
Q3 3:42 Offensive Too Many Men on Field on the Chiefs, 5 yards · pre-snap +4% DEN +0.6 pts
Q3 0:46 Illegal Formation on the Broncos, 5 yards, wiping out the play · pre-snap +6% KC +1.6 pts
Q4 15:00 Defensive Pass Interference on the Chiefs (L'Jarius Sneed), 18 yards +6% DEN +1.6 pts
Q4 0:34 Neutral Zone Infraction on the Chiefs (Justin Reid), 5 yards · pre-snap 0% DEN +0.7 pts

Chiefs penalties, every game · Broncos penalties, every game · All teams, 2023

When it happened

Broncos’ chance of winning

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 Broncos were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q2 13:13 The Chiefs fumbled and the Broncos recoveredFumble bounces · loose balls are close to 50/50 +5% DEN KC: Turnover
2 Q2 0:56 The Chiefs fumbled and the Broncos recoveredFumble bounces · loose balls are close to 50/50 +6% DEN KC: Field goal
3 Q2 0:04 H. Butker made a 56-yard field goalKicks · 62% expected for him, 35 of 48 from 45+ before +6% KC KC: Punt
4 Q3 6:40 W. Lutz had a 38-yard field goal blockedKicks · 87% expected for him +6% KC DEN: Punt
5 Q3 5:20 Defensive Holding on the Broncos (Fabian Moreau), 5 yards, wiping out the playJudgment calls · 18 flags in 3152 snaps before, position avg 1 per 216 +6% KC KC: Punt
6 Q3 0:46 Illegal Formation on the Broncos, 5 yards, wiping out the playPre-snap flags +6% KC KC: Turnover on downs
7 Q4 15:00 Defensive Pass Interference on the Chiefs (L'Jarius Sneed), 18 yardsJudgment calls · 24 flags in 3469 snaps before, position avg 1 per 216 +6% DEN DEN: Punt
8 Q4 11:24 The Chiefs fumbled and the Broncos recoveredFumble bounces · loose balls are close to 50/50 +5% DEN KC: Turnover on downs

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.

  • Kareem Jackson (DEN SS), out (IR) · 0.4 pts
  • Nick Bolton (KC LB), out (IR) · 0.4 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 1% · Broncos 99%

Final margin
Broncos by 15
Luck in points
0.5 for the Broncos
Luck-adjusted margin
Broncos by 14.5
Replay with same day's form
Chiefs 50% · Broncos 50% 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 8 2023 games · Chiefs · Broncos

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