luckadjusted

Week 2 2020 · September 20, 2020

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

Bills at Dolphins, Week 2 2020: who deserved to win?

The Bills beat the Dolphins 31–28 and were the better team on the day: replayed with the same form, they win 7 of 10. The Dolphins had the bounces: fumble bounces alone were worth 12 points of win probability to the Dolphins.

Before kickoff the Bills were 66% favorites. The biggest swing (Q4, 3:17 left): the Bills converted 3rd & 9, worth 18 points of win probability to the Bills.

Final

Buffalo Bills 31
Miami Dolphins 28

September 20, 2020 · Hard Rock Stadium · Closing line: Bills −5.5

Luck index +27 Bills lucky · −27 Dolphins

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 7, Dolphins win 3.

  1. 1 BUF 43 MIA 16
  2. 2 BUF 49 MIA 27
  3. 3 BUF 32 MIA 16
  4. 4 BUF 28 MIA 16
  5. 5 BUF 26 MIA 17
  6. 6 BUF 33 MIA 27
  7. 7 BUF 23 MIA 20
  8. 8 BUF 35 MIA 37
  9. 9 BUF 13 MIA 20
  10. 10 BUF 23 MIA 38

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 73% of them, Dolphins 27%, counting the 4% still level after regulation as half each. The line is what actually happened: Bills by 3.

Show as a table
Final margin in the replaysShare of replays
Bills by 17+27.6%
Bills by 9–1620.3%
Bills by 1–822.3%
Level after regulation4.0%
Dolphins by 1–814.0%
Dolphins by 9–167.7%
Dolphins by 17+4.3%

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 +6.2 points to the Dolphins: the final margin was Bills by 3, without the luck Bills by 9.2. 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, 39 yds made · 88% expected
  • J. Sanders, 52 yds made · 66% expected
  • J. Sanders, 45 yds made · 79% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Bills 6 for 55 yards, Dolphins 3 for 20 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 4:20 Defensive Holding on the Dolphins, 5 yards +3% BUF +1.2 pts
Q2 4:08 Illegal Blindside Block on the Bills (Isaiah McKenzie), 15 yards +3% MIA +1.3 pts
Q2 1:57 Illegal Block Above the Waist on the Bills (Taiwan Jones), 10 yards +3% MIA +0.6 pts
Q3 12:29 Illegal Block Above the Waist on the Dolphins (DeVante Parker), 10 yards, wiping out the play +13% BUF +3.1 pts
Q3 7:40 Unnecessary Roughness on the Bills (Micah Hyde), 15 yards +8% MIA +2.4 pts
Q3 2:02 False Start on the Bills, 0 yards · pre-snap 0% MIA 0.0 pts
Q4 9:24 Illegal Block Above the Waist on the Bills, 10 yards, wiping out the play +12% MIA +1.7 pts
Q4 5:55 Illegal Contact on the Bills (Tre'Davious White), 5 yards +3% MIA +0.4 pts
Q4 2:00 False Start on the Dolphins (Jakeem Grant), 5 yards · pre-snap +1% BUF +0.5 pts

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

When it happened

Dolphins’ chance of winning

As low as 0% and as high as 66%. 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 Dolphins were ahead in it, below while the Bills were.
#WhenWhat happenedWin probability forNext drive
1 Q3 12:29 Illegal Block Above the Waist on the Dolphins (DeVante Parker), 10 yards, wiping out the playJudgment calls · 1 flag in 932 snaps before, position avg 1 per 385 +13% BUF BUF: Punt
2 Q3 7:40 Unnecessary Roughness on the Bills (Micah Hyde), 15 yardsJudgment calls · 0 flags in 1161 snaps before, position avg 1 per 510 +8% MIA MIA: Turnover on downs
3 Q3 2:05 The Dolphins were stopped on 4th & 13rd & 4th downs · 67% expected +13% BUF MIA: Touchdown
4 Q4 13:46 The Dolphins fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +13% MIA MIA: Touchdown
5 Q4 10:15 The Dolphins converted 3rd & 23rd & 4th downs · 53% expected +9% MIA MIA: Touchdown
6 Q4 9:24 Illegal Block Above the Waist on the Bills, 10 yards, wiping out the playJudgment calls +12% MIA MIA: Punt
7 Q4 6:03 The Bills converted 3rd & 63rd & 4th downs · 31% expected +13% BUF BUF: Touchdown
8 Q4 3:17 The Bills converted 3rd & 93rd & 4th downs · 31% expected +18% BUF BUF: Touchdown

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.

  • Vince Biegel (MIA LB), out (IR) · 0.2 pts
  • Tremaine Edmunds (BUF LB), out · 0.6 pts
  • Matt Milano (BUF LB), out · 0.6 pts
  • Jon Feliciano (BUF G), out (IR) · 0.3 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 89% · Dolphins 11%

Final margin
Bills by 3
Luck in points
6.2 for the Dolphins
Luck-adjusted margin
Bills by 9.2
Replay with same day's form
Bills 73% · Dolphins 27% 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 2 2020 games · Bills · Dolphins

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