luckadjusted

Week 9 2023 · November 5, 2023

Dolphins vs Chiefs, Week 9 2023: who deserved to win?

The Chiefs beat the Dolphins 21–14 and were the better team on the day: replayed with the same form, they win 7 of 10.

Before kickoff it was a pick’em. The biggest swing (Q2, 0:47 left): Return touchdown by the Chiefs, worth 16 points of win probability to the Chiefs.

Final

Miami Dolphins 14
Kansas City Chiefs 21

November 5, 2023 · Deutsche Bank Park · Closing line: Chiefs −1

Luck index +32 Chiefs lucky · −32 Dolphins

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. Dolphins win 3, Chiefs win 7.

  1. 1 MIA 38 KC 19
  2. 2 MIA 30 KC 21
  3. 3 MIA 38 KC 35
  4. 4 MIA 20 KC 22
  5. 5 MIA 31 KC 36
  6. 6 MIA 14 KC 22
  7. 7 MIA 10 KC 21
  8. 8 MIA 24 KC 39
  9. 9 MIA 3 KC 22
  10. 10 MIA 6 KC 32

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

Dolphins win 32% of them, Chiefs 68%, counting the 3% still level after regulation as half each. The line is what actually happened: Chiefs by 7.

Show as a table
Final margin in the replaysShare of replays
Dolphins by 17+5.5%
Dolphins by 9–168.5%
Dolphins by 1–816.2%
Level after regulation3.4%
Chiefs by 1–823.1%
Chiefs by 9–1620.8%
Chiefs by 17+22.5%

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 +0.7 points to the Dolphins: the final margin was Chiefs by 7, without the luck Chiefs by 7.7. Luck shares are the fitted ones (how much of each kind is luck).

Penalties: Dolphins 6 for 45 yards, Chiefs 9 for 69 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 10:01 False Start on the Dolphins (Chase Claypool), 5 yards · pre-snap +1% KC +0.5 pts
Q1 10:01 Neutral Zone Infraction on the Chiefs (Chris Jones), 5 yards · pre-snap +1% MIA +0.4 pts
Q1 5:20 Defensive Holding on the Chiefs (L'Jarius Sneed), 5 yards, wiping out the play +1% KC +0.2 pts
Q1 3:20 Illegal Shift on the Dolphins (Cedrick Wilson Jr.), 5 yards, wiping out the play · pre-snap +6% KC +2.4 pts
Q2 11:45 Intentional Grounding on the Dolphins (Tua Tagovailoa), 10 yards +2% KC +1.2 pts
Q2 11:04 Offensive Holding on the Chiefs (Bryan Cook), 4 yards +1% MIA +0.3 pts
Q2 8:28 Defensive Holding on the Dolphins (Bradley Chubb), 5 yards +1% KC +0.5 pts
Q2 5:04 False Start on the Chiefs, 5 yards · pre-snap +2% MIA +0.7 pts
Q3 14:23 Offensive Holding on the Dolphins, 10 yards, wiping out the play +1% KC +2.1 pts
Q3 13:24 Offensive Holding on the Chiefs (Jack Cochrane), 10 yards 0% MIA +0.9 pts
Q3 11:27 Offensive Holding on the Chiefs, 10 yards, wiping out the play +1% MIA +2.4 pts
Q3 5:56 Defensive Holding on the Chiefs (L'Jarius Sneed), 5 yards 0% KC +0.2 pts
Q3 2:46 Offensive Holding on the Chiefs, 11 yards, wiping out the play +2% MIA +1.8 pts
Q3 2:12 Offensive Holding on the Dolphins, 10 yards +4% KC +1.5 pts
Q3 0:58 Unnecessary Roughness on the Chiefs (Chris Jones), 14 yards +3% MIA +1.0 pts

Dolphins 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 Dolphins were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:14 The Chiefs converted 3rd & 23rd & 4th downs · 63% expected +6% KC KC: Touchdown
2 Q1 3:20 Illegal Shift on the Dolphins (Cedrick Wilson Jr.), 5 yards, wiping out the playPre-snap flags · 3 flags in 1519 snaps before, position avg 1 per 420 +6% KC KC: Punt
3 Q2 9:41 The Chiefs converted 3rd & 53rd & 4th downs · 43% expected +4% KC KC: Touchdown
4 Q2 0:47 The Dolphins fumbled and the Chiefs recoveredFumble bounces · loose balls are close to 50/50Return touchdown by the ChiefsSpecial teams +16% KC MIA: Punt
5 Q3 2:20 The Chiefs were stopped on 3rd & 203rd & 4th downs · 19% expectedThe Chiefs fumbled and the Dolphins recoveredFumble bounces · loose balls are close to 50/50 +9% MIA KC: Punt
6 Q4 10:45 The Dolphins fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +9% MIA MIA: Punt
7 Q4 1:07 The Dolphins were stopped on 3rd & 103rd & 4th downs · 25% expected +4% KC MIA: Turnover on downs
8 Q4 1:03 The Dolphins were stopped on 4th & 103rd & 4th downs · 25% expectedThe Dolphins fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +7% KC MIA: 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.

  • Nick Bolton (KC LB), out (IR) · 0.4 pts
  • Robert Hunt (MIA G), out · 0.4 pts
  • Isaiah Wynn (MIA G), 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

Dolphins 11% · Chiefs 89%

Final margin
Chiefs by 7
Luck in points
0.7 for the Dolphins
Luck-adjusted margin
Chiefs by 7.7
Replay with same day's form
Dolphins 32% · Chiefs 68% 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 2023 games · Dolphins · Chiefs

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