luckadjusted

Week 17 2022 · January 1, 2023

Broncos at Chiefs, Week 17 2022: who deserved to win?

The Chiefs beat the Broncos 27–24, and it was no fluke: replayed with the way both teams actually played, the Chiefs win 10 of 10. The Broncos had the bounces: kicks alone were worth 15 points of win probability to the Broncos.

Before kickoff the Chiefs were 84% favorites. The game turned on a luck play (Q3, 4:17 left): Offensive Pass Interference on the Broncos (Courtland Sutton), 8 yards, wiping out the play, worth 23 points of win probability to the Chiefs.

Final

Denver Broncos 24
Kansas City Chiefs 27

January 1, 2023 · GEHA Field at Arrowhead Stadium · Closing line: Chiefs −13.5

Luck index +3 Chiefs about even · −3 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 0, Chiefs win 10.

  1. 1 DEN 27 KC 30
  2. 2 DEN 34 KC 40
  3. 3 DEN 10 KC 20
  4. 4 DEN 16 KC 29
  5. 5 DEN 16 KC 33
  6. 6 DEN 21 KC 41
  7. 7 DEN 10 KC 33
  8. 8 DEN 3 KC 29
  9. 9 DEN 10 KC 40
  10. 10 DEN 17 KC 55

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 3% of them, Chiefs 97%, counting the 1% still level after regulation as half each. The line is what actually happened: Chiefs by 3.

Show as a table
Final margin in the replaysShare of replays
Broncos by 17+0.1%
Broncos by 9–160.5%
Broncos by 1–82.3%
Level after regulation0.5%
Chiefs by 1–86.9%
Chiefs by 9–1615.5%
Chiefs by 17+74.2%

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 +4.2 points to the Broncos: the final margin was Chiefs by 3, without the luck Chiefs by 7.2. 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.

  • B. McManus, 49 yds made · 77% expected
  • H. Butker, 51 yds blocked · 74% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Broncos 3 for 23 yards, Chiefs 5 for 31 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
Q2 11:48 Defensive Holding on the Chiefs, 5 yards +3% DEN +0.8 pts
Q2 4:04 Offensive Holding on the Chiefs, 10 yards +4% DEN +1.0 pts
Q2 1:57 Defensive Holding on the Broncos, 5 yards +4% KC +1.2 pts
Q3 13:17 Offensive Holding on the Broncos (Eric Saubert), 10 yards +4% KC +1.0 pts
Q3 7:09 Neutral Zone Infraction on the Chiefs (Chris Jones), 4 yards · pre-snap +2% DEN +0.3 pts
Q3 4:17 Offensive Pass Interference on the Broncos (Courtland Sutton), 8 yards, wiping out the play +23% KC +4.1 pts
Q4 11:09 Defensive Pass Interference on the Chiefs, 7 yards +2% DEN +1.6 pts
Q4 8:10 Illegal Use of Hands on the Chiefs, 5 yards, wiping out the play +13% DEN +6.9 pts

Broncos penalties, every game · Chiefs penalties, every game · All teams, 2022

When it happened

Chiefs’ chance of winning

As low as 28% and as high as 100%. 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 Q2 7:57 The Chiefs were stopped on 3rd & 103rd & 4th downs · 27% expectedThe Chiefs threw an interception-worthy pass, and it was pickedInterceptions · 47% expected to stay out of the defense's hands +14% DEN KC: Touchdown
2 Q2 4:59 The Chiefs fumbled and the Broncos recoveredFumble bounces · loose balls are close to 50/50 +9% DEN KC: Touchdown
3 Q2 0:54 The Broncos converted 3rd & 93rd & 4th downs · 25% expected +10% DEN DEN: Turnover
4 Q2 0:16 The Broncos fumbled and the Chiefs recoveredFumble bounces · loose balls are close to 50/50 +10% KC DEN: Punt
5 Q2 0:05 H. Butker had a 51-yard field goal blockedKicks · 74% expected for him, 30 of 42 from 45+ before +13% DEN KC: Punt
6 Q3 4:17 The game turned hereOffensive Pass Interference on the Broncos (Courtland Sutton), 8 yards, wiping out the playJudgment calls · 9 flags in 2656 snaps before, position avg 1 per 412 +23% KC KC: Touchdown
7 Q4 8:10 Illegal Use of Hands on the Chiefs, 5 yards, wiping out the playJudgment calls +13% DEN DEN: Touchdown
8 Q4 1:21 The Broncos were stopped on 4th & 23rd & 4th downs · 56% expected +19% KC –

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.

  • Dre'Mont Jones (DEN DE), out (IR) · 0.7 pts
  • Calvin Anderson (DEN T), out · 0.6 pts
  • Greg Dulcich (DEN TE), out (IR) · 0.3 pts
  • D.J. Jones (DEN DT), out · 0.3 pts
  • Freddie Swain (DEN WR), out · 0.3 pts
  • Baron Browning (DEN LB), out · 0.2 pts
  • Mitchell Fraboni (DEN LS), out (IR) · 0.1 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 18% · Chiefs 82%

Final margin
Chiefs by 3
Luck in points
4.2 for the Broncos
Luck-adjusted margin
Chiefs by 7.2
Replay with same day's form
Broncos 3% · Chiefs 97% 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 17 2022 games · Broncos · Chiefs

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