luckadjusted

Week 13 2020 · December 6, 2020

No FTN charting for this game (drops and interception-worthy throws are not modelled).

Broncos at Chiefs, Week 13 2020: who deserved to win?

The Chiefs beat the Broncos 22–16, and it was no fluke: replayed with the way both teams actually played, the Chiefs win 9 of 10. The Broncos had the bounces: judgment calls alone were worth 6.0 points to the Broncos.

Before kickoff the Chiefs were 83% favorites. The biggest swing (Q4, 10:16 left): Offensive Holding on the Chiefs, 10 yards, wiping out the play, worth 32 points of win probability to the Broncos.

Final

Denver Broncos 16
Kansas City Chiefs 22

December 6, 2020 · Arrowhead Stadium · Closing line: Chiefs −13

Luck index +11 Chiefs about even · −11 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 16 KC 10
  2. 2 DEN 17 KC 19
  3. 3 DEN 34 KC 38
  4. 4 DEN 16 KC 23
  5. 5 DEN 31 KC 41
  6. 6 DEN 20 KC 33
  7. 7 DEN 13 KC 30
  8. 8 DEN 13 KC 33
  9. 9 DEN 10 KC 35
  10. 10 DEN 14 KC 45

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 11% of them, Chiefs 89%, counting the 2% still level after regulation as half each. The line is what actually happened: Chiefs by 6.

Show as a table
Final margin in the replaysShare of replays
Broncos by 17+0.6%
Broncos by 9–162.4%
Broncos by 1–86.3%
Level after regulation2.0%
Chiefs by 1–818.5%
Chiefs by 9–1623.4%
Chiefs by 17+46.9%

Where the luck was

Take the luck out

The final margin was Chiefs by 6. Remove the luck, one kind at a time, and it becomes Chiefs by 10.9.

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).

The kicks

How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.

  • B. McManus, 53 yds made · 69% expected
  • H. Butker, 35 yds made · 93% expected
  • H. Butker, 24 yds made · 99% expected
  • B. McManus, 57 yds missed · 62% expected
  • H. Butker, 23 yds made · 99% expected
  • H. Butker, 31 yds made · 96% expected
  • H. Butker, 48 yds made · 74% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Chiefs’ chance of winning

As low as 32% 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 Q1 13:44 The Broncos converted 3rd & 73rd & 4th downs · 32% expected +14% DEN DEN: Turnover
2 Q2 9:12 The Broncos converted 3rd & 33rd & 4th downs · 50% expected +16% DEN DEN: Touchdown
3 Q2 3:28 The Chiefs were stopped on 3rd & 13rd & 4th downs · 71% expected +7% DEN KC: Field goal
4 Q2 0:33 B. McManus missed 57-yard field goalKicks · 62% expected for him, 20 of 25 from 45+ before +9% KC DEN: Touchdown
5 Q3 11:18 The Chiefs were stopped on 3rd & 83rd & 4th downs · 29% expected +8% DEN KC: Field goal
6 Q4 10:16 Offensive Holding on the Chiefs, 10 yards, wiping out the playJudgment calls +32% DEN DEN: Punt
7 Q4 1:09 H. Butker made 48-yard field goalKicks · 74% expected for him, 9 of 13 from 45+ before +8% DEN KC: End of game
8 Q4 0:33 The Broncos were stopped on 4th & 53rd & 4th downs · 39% expected +7% 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.

  • Mitchell Schwartz (KC T), out (IR) · 1.5 pts
  • Kelechi Osemele (KC G), out (IR) · 0.3 pts
  • Clyde Edwards-Helaire (KC RB), out · 0.2 pts
  • Bryce Callahan (DEN CB), out (IR) · 0.6 pts
  • Mike Purcell (DEN DL), out (IR) · 0.3 pts
  • Jake Butt (DEN TE), 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 12% · Chiefs 88%

Final margin
Chiefs by 6
Luck in points
4.9 for the Broncos
Luck-adjusted margin
Chiefs by 10.9
Replay with same day's form
Broncos 11% · Chiefs 89% 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 (not available for this game); injuries from snap counts and injury reports. No FTN charting for this game (drops and interception-worthy throws are not modelled).

Methodology and validation · All Week 13 2020 games · Broncos · Chiefs

More from Week 13 2020