luckadjusted

Week 15 2020 · December 20, 2020

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

Chiefs at Saints, Week 15 2020: who deserved to win?

The Chiefs beat the Saints 32–29 and were the better team on the day: replayed with the same form, they win 6 of 10. The Saints had the bounces: fumble bounces alone were worth 1.6 points to the Saints.

Before kickoff the Chiefs were 57% favorites. The biggest swing (Q1, 11:39 left): Illegal Contact on the Saints (Malcolm Jenkins), 5 yards, wiping out the play, worth 13 points of win probability to the Chiefs.

Final

Kansas City Chiefs 32
New Orleans Saints 29

December 20, 2020 · Mercedes-Benz Superdome · Closing line: Chiefs −2.5

Luck index +35 Chiefs lucky · −35 Saints

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. Chiefs win 6, Saints win 4.

  1. 1 KC 47 NO 17
  2. 2 KC 29 NO 9
  3. 3 KC 45 NO 31
  4. 4 KC 39 NO 30
  5. 5 KC 45 NO 40
  6. 6 KC 42 NO 40
  7. 7 KC 24 NO 27
  8. 8 KC 26 NO 35
  9. 9 KC 21 NO 33
  10. 10 KC 20 NO 40

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

Chiefs win 65% of them, Saints 35%, counting the 3% 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
Chiefs by 17+21.7%
Chiefs by 9–1618.3%
Chiefs by 1–822.7%
Level after regulation2.7%
Saints by 1–817.3%
Saints by 9–1610.4%
Saints by 17+7.0%

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 Saints by 6.5.

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).

When it happened

Saints’ chance of winning

As low as 0% and as high as 63%. 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 Saints were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q1 11:39 Illegal Contact on the Saints (Malcolm Jenkins), 5 yards, wiping out the playJudgment calls · 7 flags in 2071 snaps before, position avg 1 per 510 +13% KC KC: Punt
2 Q1 9:39 The Saints were stopped on 3rd & 53rd & 4th downs · 43% expected +12% KC NO: Punt
3 Q2 11:38 The Saints converted 3rd & 103rd & 4th downs · 29% expected +8% NO NO: Touchdown
4 Q3 14:17 Defensive Pass Interference on the Chiefs (L'Jarius Sneed), 19 yardsJudgment calls · 2 flags in 328 snaps before, position avg 1 per 207 +10% NO NO: Touchdown
5 Q3 11:00 The Chiefs converted 3rd & 53rd & 4th downs · 44% expected +9% KC KC: Touchdown
6 Q3 3:43 The Saints were stopped on 3rd & 63rd & 4th downs · 39% expectedIntentional Grounding on the Saints (Drew Brees), 10 yardsJudgment calls · 1 flag in 1232 snaps before, position avg 1 per 669 +9% KC NO: Punt
7 Q4 11:04 The Chiefs were stopped on 3rd & 103rd & 4th downs · 30% expectedThe Chiefs fumbled and the Saints recoveredFumble bounces · loose balls are close to 50/50 +9% NO KC: Field goal
8 Q4 1:45 Face Mask on the Saints (Demario Davis), 15 yardsJudgment calls · 5 flags in 1885 snaps before, position avg 1 per 395 +9% KC KC: End of game

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.

  • Michael Thomas (NO WR), out (IR) · 1.1 pts
  • Nick Easton (NO C/G), out · 0.2 pts
  • Mike Remmers (KC T), out · 0.6 pts
  • Damien Wilson (KC LB), 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

Chiefs 17% · Saints 83%

Final margin
Chiefs by 3
Luck in points
9.5 for the Chiefs
Luck-adjusted margin
Saints by 6.5
Replay with same day's form
Chiefs 65% · Saints 35% 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 15 2020 games · Chiefs · Saints

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