luckadjusted
NFL Week 9 · 2026

Week 6 2023 · October 12, 2023

Broncos at Chiefs, Week 6 2023: who deserved to win?

The Chiefs beat the Broncos 19–8, and the replays back it up: with the way both teams actually played, the Chiefs win 9 of 10.

Before kickoff the Chiefs were 78% favorites. The biggest swing (Q2, 1:28 left): Defensive Pass Interference on the Broncos (Damarri Mathis), 24 yards, wiping out the play, worth 10 points of win probability to the Chiefs.

Final

Denver Broncos 8
Kansas City Chiefs 19

October 12, 2023 · GEHA Field at Arrowhead Stadium · Closing line: Chiefs −10.5

Luck index +14 Chiefs about even · −14 Broncos

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. Broncos win 1, Chiefs win 9.

  1. 1 DEN 27 KC 21
  2. 2 DEN 21 KC 23
  3. 3 DEN 10 KC 14
  4. 4 DEN 13 KC 19
  5. 5 DEN 17 KC 26
  6. 6 DEN 14 KC 27
  7. 7 DEN 22 KC 37
  8. 8 DEN 10 KC 28
  9. 9 DEN 14 KC 37
  10. 10 DEN 3 KC 34

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

Broncos win 14% of them, Chiefs 86%, counting the 1% still level after regulation as half each. The line is what actually happened: Chiefs by 11.

Show as a table
Final margin in the replaysShare of replays
Broncos by 17+1.2%
Broncos by 9–163.7%
Broncos by 1–88.1%
Level after regulation1.4%
Chiefs by 1–821.1%
Chiefs by 9–1623.4%
Chiefs by 17+41.2%

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 +5.1 points to the Chiefs: the final margin was Chiefs by 11, without the luck Chiefs by 5.9. 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, 35 yds made · 94% expected
  • H. Butker, 60 yds made · 60% expected
  • H. Butker, 25 yds made · 99% expected
  • H. Butker, 52 yds made · 69% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Broncos 3 for 34 yards, Chiefs 7 for 84 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
Q2 13:15 Neutral Zone Infraction on the Broncos (Ronnie Perkins), 5 yards · pre-snap +3% KC +1.4 pts
Q2 12:24 Offensive Holding on the Chiefs, 10 yards +1% DEN +1.0 pts
Q2 3:06 False Start on the Chiefs, 5 yards · pre-snap 0% DEN 0.0 pts
Q2 1:28 Defensive Pass Interference on the Broncos (Damarri Mathis), 24 yards, wiping out the play +10% KC +4.2 pts
Q2 1:08 Intentional Grounding on the Chiefs (Patrick Mahomes), 16 yards +2% DEN +1.5 pts
Q2 0:22 Illegal Touch Kick on the Broncos (Riley Moss), 5 yards +1% KC +0.5 pts
Q3 8:39 Defensive Pass Interference on the Chiefs (Jaylen Watson), 17 yards +2% DEN +1.5 pts
Q4 13:00 Offensive Holding on the Chiefs (Cam Jones), 10 yards 0% DEN +0.9 pts
Q4 10:43 Illegal Blindside Block on the Chiefs (Marquez Valdes-Scantling), 15 yards 0% DEN +1.4 pts
Q4 6:16 Roughing the Passer on the Chiefs (Mike Edwards), 11 yards +2% DEN +1.3 pts

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

When it happened

Chiefs’ 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 Chiefs were ahead in it, below while the Broncos were.
#WhenWhat happenedWin probability forNext drive
1 Q1 9:32 The Broncos were stopped on 4th & 33rd & 4th downs · 50% expected +7% KC DEN: Turnover
2 Q1 5:00 The Broncos threw an interception-worthy pass, and it was pickedInterceptions · defenses catch 49% of interception-worthy throws +5% KC DEN: Punt
3 Q1 3:04 The Chiefs threw an interception-worthy pass, and it was pickedInterceptions · defenses catch 49% of interception-worthy throws +4% DEN KC: Turnover on downs
4 Q2 11:35 The Chiefs converted 3rd & 83rd & 4th downs · 36% expected +5% KC KC: Turnover on downs
5 Q2 8:10 The Chiefs were stopped on 4th & 23rd & 4th downs · 58% expected +6% DEN KC: Touchdown
6 Q2 6:36 The Chiefs fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +6% KC KC: Touchdown
7 Q2 1:28 Defensive Pass Interference on the Broncos (Damarri Mathis), 24 yards, wiping out the playJudgment calls · 8 flags in 1209 snaps before, position avg 1 per 216 +10% KC KC: Punt
8 Q2 0:28 The Broncos were stopped on 3rd & 53rd & 4th downs · 37% expected +4% KC DEN: 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.

  • D.J. Jones (DEN NT), out · 0.2 pts
  • Baron Browning (DEN LB), out (IR) · 0.2 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

Broncos 14% · Chiefs 86%

Final margin
Chiefs by 11
Luck in points
5.1 for the Chiefs
Luck-adjusted margin
Chiefs by 5.9
Replay with same day's form
Broncos 14% · Chiefs 86% 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 6 2023 games · Broncos · Chiefs

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