luckadjusted

Week 6 2020 · October 19, 2020

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

Chiefs at Bills, Week 6 2020: who deserved to win?

The Chiefs beat the Bills 26–17, but it was a coin flip: replayed with the way both teams played, the Chiefs win 5 of 10. Luck ran their way: 3rd & 4th downs alone were worth 13 points of win probability to the Chiefs.

Before kickoff the Chiefs were 66% favorites. The biggest swing (Q2, 0:01 left): T. Bass missed 52-yard field goal, worth 10 points of win probability to the Chiefs.

Final

Kansas City Chiefs 26
Buffalo Bills 17

October 19, 2020 · New Era Field · Closing line: Chiefs −5.5

Luck index +48 Chiefs lucky · −48 Bills

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 5, Bills win 5.

  1. 1 KC 31 BUF 10
  2. 2 KC 31 BUF 17
  3. 3 KC 34 BUF 24
  4. 4 KC 28 BUF 23
  5. 5 KC 33 BUF 31
  6. 6 KC 8 BUF 10
  7. 7 KC 23 BUF 27
  8. 8 KC 31 BUF 38
  9. 9 KC 14 BUF 26
  10. 10 KC 17 BUF 36

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 52% of them, Bills 48%, counting the 8% still level after regulation as half each. The line is what actually happened: Chiefs by 9.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+9.4%
Chiefs by 9–1612.8%
Chiefs by 1–824.8%
Level after regulation8.2%
Bills by 1–824.9%
Bills by 9–1612.4%
Bills by 17+7.5%

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 +1.1 points to the Chiefs: the final margin was Chiefs by 9, without the luck Chiefs by 7.9. 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.

  • T. Bass, 48 yds made · 75% expected
  • T. Bass, 52 yds missed · 68% expected
  • H. Butker, 37 yds made · 91% expected
  • H. Butker, 30 yds made · 97% expected
  • Extra point missed · 93% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Chiefs 8 for 68 yards, Bills 4 for 39 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 11:35 Defensive Pass Interference on the Chiefs, 24 yards +10% BUF +3.0 pts
Q2 5:07 Offensive Holding on the Chiefs, 10 yards +2% BUF +0.9 pts
Q2 3:36 Illegal Use of Hands on the Chiefs (Bashaud Breeland), 5 yards +3% BUF +0.7 pts
Q2 2:18 Illegal Contact on the Chiefs (Bashaud Breeland), 5 yards +7% BUF +1.0 pts
Q3 8:33 False Start on the Chiefs, 5 yards · pre-snap +1% BUF +1.0 pts
Q4 14:40 Offensive Holding on the Chiefs (Thakarius Keyes), 6 yards 0% BUF +0.5 pts
Q4 14:40 False Start on the Bills, 4 yards · pre-snap +1% KC +0.8 pts
Q4 13:51 Unnecessary Roughness on the Bills (Tre'Davious White), 15 yards +3% KC +1.7 pts
Q4 12:50 Unnecessary Roughness on the Bills (Jordan Poyer), 15 yards +3% KC +2.0 pts
Q4 8:42 Defensive Pass Interference on the Chiefs (Bashaud Breeland), 8 yards 0% KC +0.4 pts
Q4 8:06 Illegal Use of Hands on the Chiefs, 5 yards +2% BUF +0.9 pts
Q4 1:34 False Start on the Bills (Stefon Diggs), 5 yards · pre-snap +1% KC +0.4 pts

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

When it happened

Bills’ chance of winning

As low as 0% and as high as 64%. 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 Bills were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q2 11:35 Defensive Pass Interference on the Chiefs, 24 yardsJudgment calls +10% BUF BUF: Touchdown
2 Q2 11:22 The Chiefs fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +7% KC KC: Touchdown
3 Q2 10:03 The Chiefs converted 3rd & 63rd & 4th downs · 42% expected +6% KC KC: Touchdown
4 Q2 5:01 The Chiefs converted 3rd & 73rd & 4th downs · 39% expected +10% KC KC: Touchdown
5 Q2 2:18 Illegal Contact on the Chiefs (Bashaud Breeland), 5 yardsJudgment calls · 10 flags in 1164 snaps before, position avg 1 per 237 +7% BUF BUF: Punt
6 Q2 0:01 T. Bass missed 52-yard field goalKicks · 68% expected for him, 1 of 1 from 45+ before +10% KC BUF: Punt
7 Q3 1:24 The Chiefs converted 4th & 13rd & 4th downs · 78% expected +9% KC KC: Touchdown
8 Q4 4:24 The Chiefs converted 3rd & 123rd & 4th downs · 29% expected +7% KC KC: Field goal

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.

  • Dawson Knox (BUF TE), out · 0.6 pts
  • Matt Milano (BUF LB), out · 0.5 pts
  • Trent Murphy (BUF DE), out · 0.5 pts
  • Levi Wallace (BUF CB), out (IR) · 0.3 pts
  • Quinton Spain (BUF G), out · 0.3 pts
  • Sammy Watkins (KC WR), out · 0.8 pts
  • Kelechi Osemele (KC G), out (IR) · 0.5 pts
  • L'Jarius Sneed (KC CB), out (IR) · 0.5 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 92% · Bills 8%

Final margin
Chiefs by 9
Luck in points
1.1 for the Chiefs
Luck-adjusted margin
Chiefs by 7.9
Replay with same day's form
Chiefs 52% · Bills 48% 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 6 2020 games · Chiefs · Bills

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