luckadjusted

Week 15 2020 · December 19, 2020

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

Bills at Broncos, Week 15 2020: who deserved to win?

The Bills beat the Broncos 48–19, and it was no fluke: replayed with the way both teams actually played, the Bills win 9 of 10. The Broncos had the bounces: judgment calls alone were worth 7.0 points to the Broncos.

Before kickoff the Bills were 66% favorites. The biggest swing (Q1, 6:22 left): Defensive Offside on the Broncos (Jeremiah Attaochu), 5 yards, wiping out the play, worth 15 points of win probability to the Bills.

Final

Buffalo Bills 48
Denver Broncos 19

December 19, 2020 · Empower Field at Mile High · Closing line: Bills −5.5

Luck index +6 Bills about even · −6 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. Bills win 9, Broncos win 1.

  1. 1 BUF 41 DEN 6
  2. 2 BUF 37 DEN 9
  3. 3 BUF 40 DEN 16
  4. 4 BUF 34 DEN 14
  5. 5 BUF 35 DEN 19
  6. 6 BUF 48 DEN 35
  7. 7 BUF 34 DEN 24
  8. 8 BUF 34 DEN 28
  9. 9 BUF 30 DEN 27
  10. 10 BUF 17 DEN 23

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

Bills win 94% of them, Broncos 6%, counting the 2% still level after regulation as half each. The line is what actually happened: Bills by 29.

Show as a table
Final margin in the replaysShare of replays
Bills by 17+58.3%
Bills by 9–1619.4%
Bills by 1–814.5%
Level after regulation1.8%
Broncos by 1–84.3%
Broncos by 9–161.3%
Broncos by 17+0.3%

Where the luck was

Take the luck out

The final margin was Bills by 29. Remove the luck, one kind at a time, and it becomes Bills by 28.6.

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.

  • T. Russolino, 51 yds missed · 59% expected
  • T. Bass, 27 yds made · 96% expected
  • T. Bass, 27 yds made · 96% expected
  • Extra point missed · 93% expected
  • Extra point missed · 93% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Broncos’ 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 Broncos were ahead in it, below while the Bills were.
#WhenWhat happenedWin probability forNext drive
1 Q1 12:24 The Broncos converted 3rd & 63rd & 4th downs · 33% expected +9% DEN DEN: Missed field goal
2 Q1 8:12 The Bills converted 3rd & 83rd & 4th downs · 36% expected +10% BUF BUF: Touchdown
3 Q1 7:05 The Bills fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +6% BUF BUF: Touchdown
4 Q1 6:22 Defensive Offside on the Broncos (Jeremiah Attaochu), 5 yards, wiping out the playPre-snap flags · 2 flags in 834 snaps before, position avg 1 per 402 +15% BUF BUF: Touchdown
5 Q2 10:37 The Bills converted 3rd & 53rd & 4th downs · 46% expected +6% BUF BUF: Touchdown
6 Q2 6:34 The Broncos converted 3rd & 83rd & 4th downs · 22% expected +7% DEN DEN: Touchdown
7 Q2 0:05 The Broncos missed an extra pointKicks · extra points are made about 94% of the time +6% BUF DEN: Opp touchdown
8 Q3 10:58 The Broncos fumbled and the Bills recoveredFumble bounces · loose balls are close to 50/50Return touchdown by the BillsSpecial teams +9% BUF DEN: Punt

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.

  • Demar Dotson (DEN T), out · 0.6 pts
  • Bryce Callahan (DEN CB), out (IR) · 0.6 pts
  • A.J. Bouye (DEN CB), out (IR) · 0.6 pts
  • Brandon McManus (DEN K), out (IR) · 0.3 pts
  • John Brown (BUF WR), out (IR) · 0.6 pts
  • Cody Ford (BUF T), out (IR) · 0.3 pts
  • Tyler Kroft (BUF TE), 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

Bills 100% · Broncos 0%

Final margin
Bills by 29
Luck in points
0.4 for the Bills
Luck-adjusted margin
Bills by 28.6
Replay with same day's form
Bills 94% · Broncos 6% 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 · Bills · Broncos

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