luckadjusted

Week 16 2020 · December 27, 2020

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

Falcons at Chiefs, Week 16 2020: who deserved to win?

The Chiefs beat the Falcons 17–14, and it was no fluke: replayed with the way both teams actually played, the Chiefs win 9 of 10. The Falcons had the bounces: 3rd & 4th downs alone were worth 1.9 points to the Falcons.

Before kickoff the Chiefs were 79% favorites. The biggest swing (Q4, 0:14 left): Y. Koo missed 39-yard field goal, worth 28 points of win probability to the Chiefs.

Final

Atlanta Falcons 14
Kansas City Chiefs 17

December 27, 2020 · Arrowhead Stadium · Closing line: Chiefs −11

Luck index +13 Chiefs about even · −13 Falcons

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. Falcons win 1, Chiefs win 9.

  1. 1 ATL 20 KC 14
  2. 2 ATL 18 KC 20
  3. 3 ATL 20 KC 24
  4. 4 ATL 17 KC 24
  5. 5 ATL 28 KC 38
  6. 6 ATL 28 KC 41
  7. 7 ATL 13 KC 30
  8. 8 ATL 14 KC 34
  9. 9 ATL 6 KC 30
  10. 10 ATL 14 KC 44

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

Falcons win 13% of them, Chiefs 87%, counting the 2% 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
Falcons by 17+1.1%
Falcons by 9–162.5%
Falcons by 1–88.8%
Level after regulation1.8%
Chiefs by 1–819.7%
Chiefs by 9–1624.5%
Chiefs by 17+41.6%

Where the luck was

Take the luck out

The final margin was Chiefs by 3. Remove the luck, one kind at a time, and it becomes Falcons by 1.8.

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.

  • H. Butker, 53 yds made · 67% expected
  • Y. Koo, 39 yds missed · 89% 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 24% 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 Falcons were.
#WhenWhat happenedWin probability forNext drive
1 Q2 11:17 The Chiefs converted 4th & 13rd & 4th downs · 77% expected +9% KC KC: Turnover
2 Q3 10:42 The Chiefs were stopped on 3rd & 73rd & 4th downs · 31% expected +21% ATL KC: Punt
3 Q3 1:00 The Chiefs converted 3rd & 113rd & 4th downs · 30% expectedFalse Start on the Chiefs (Mecole Hardman), 5 yardsPre-snap flags · 2 flags in 1267 snaps before, position avg 1 per 385 +11% KC KC: Field goal
4 Q4 10:50 The Falcons fumbled and the Chiefs recoveredFumble bounces · loose balls are close to 50/50 +14% KC ATL: Touchdown
5 Q4 7:58 Offensive Holding on the Falcons, 10 yards, wiping out the playJudgment calls +10% KC KC: Touchdown
6 Q4 5:21 The Falcons converted 3rd & 43rd & 4th downs · 48% expected +11% ATL ATL: Touchdown
7 Q4 0:19 The Falcons were stopped on 3rd & 53rd & 4th downs · 44% expected +11% KC ATL: Missed field goal
8 Q4 0:14 Y. Koo missed 39-yard field goalKicks · 89% expected for him +28% 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.

  • Anthony Hitchens (KC LB), out (IR) · 0.3 pts
  • Damien Wilson (KC LB), out · 0.2 pts
  • Clyde Edwards-Helaire (KC RB), out · 0.1 pts
  • Julio Jones (ATL WR), out · 1.3 pts
  • Alex Mack (ATL C), out · 0.8 pts
  • James Carpenter (ATL G), out · 0.4 pts
  • Darqueze Dennard (ATL DB), out · 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

Falcons 48% · Chiefs 52%

Final margin
Chiefs by 3
Luck in points
4.8 for the Chiefs
Luck-adjusted margin
Falcons by 1.8
Replay with same day's form
Falcons 13% · Chiefs 87% 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 16 2020 games · Falcons · Chiefs

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