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.

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 34 KC 28
  2. 2 ATL 21 KC 23
  3. 3 ATL 29 KC 33
  4. 4 ATL 24 KC 31
  5. 5 ATL 24 KC 34
  6. 6 ATL 21 KC 34
  7. 7 ATL 0 KC 17
  8. 8 ATL 21 KC 41
  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

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 +4.8 points to the Chiefs: the final margin was Chiefs by 3, without the luck Falcons by 1.8. 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, 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.

Penalties: Falcons 7 for 45 yards, Chiefs 6 for 41 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 11:13 Defensive Offside on the Falcons (Grady Jarrett), 5 yards, wiping out the play · pre-snap +5% KC +2.1 pts
Q1 5:58 Illegal Shift on the Falcons, 5 yards, wiping out the play · pre-snap +4% KC +1.4 pts
Q1 3:32 False Start on the Falcons, 5 yards · pre-snap +2% KC +0.2 pts
Q2 10:39 False Start on the Chiefs (Travis Kelce), 5 yards · pre-snap +2% ATL +0.6 pts
Q3 14:25 Neutral Zone Infraction on the Falcons (Foyesade Oluokun), 5 yards · pre-snap +4% KC +0.9 pts
Q3 4:46 False Start on the Falcons, 5 yards · pre-snap +2% KC +0.5 pts
Q3 3:50 Defensive Pass Interference on the Chiefs, 11 yards +8% ATL +2.5 pts
Q3 3:04 Offensive Holding on the Falcons, 10 yards +5% KC +1.6 pts
Q3 1:00 False Start on the Chiefs (Mecole Hardman), 5 yards · pre-snap +3% ATL +0.7 pts
Q4 7:58 Offensive Holding on the Falcons, 10 yards, wiping out the play +10% KC +1.8 pts
Q4 4:18 Illegal Block Above the Waist on the Chiefs (Tyreek Hill), 10 yards +5% ATL +0.9 pts
Q4 1:55 Defensive Holding on the Chiefs, 5 yards 0% ATL +0.3 pts
Q4 0:33 Defensive Offside on the Chiefs (Alex Okafor), 5 yards · pre-snap +1% ATL +0.5 pts

Falcons penalties, every game · Chiefs penalties, every game · All teams, 2020

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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