luckadjusted

Week 18 2021 · January 9, 2022

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

Patriots at Dolphins, Week 18 2021: who deserved to win?

The Dolphins beat the Patriots 33–24, but the Patriots played well enough to win it: they take 7 of 10 replays with the same day's form.

Before kickoff the Patriots were 67% favorites. The biggest swing (Q1, 6:16 left): the Patriots were stopped on 3rd & 1, worth 30 points of win probability to the Dolphins.

Final

New England Patriots 24
Miami Dolphins 33

January 9, 2022 · Hard Rock Stadium · Closing line: Patriots −6

Luck index +72 Dolphins very lucky · −72 Patriots

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. Patriots win 7, Dolphins win 3.

  1. 1 NE 37 MIA 10
  2. 2 NE 31 MIA 12
  3. 3 NE 31 MIA 17
  4. 4 NE 17 MIA 6
  5. 5 NE 23 MIA 15
  6. 6 NE 23 MIA 17
  7. 7 NE 13 MIA 10
  8. 8 NE 10 MIA 13
  9. 9 NE 23 MIA 30
  10. 10 NE 10 MIA 25

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

Patriots win 72% of them, Dolphins 28%, counting the 5% still level after regulation as half each. The line is what actually happened: Dolphins by 9.

Show as a table
Final margin in the replaysShare of replays
Patriots by 17+23.6%
Patriots by 9–1621.6%
Patriots by 1–826.1%
Level after regulation4.9%
Dolphins by 1–814.4%
Dolphins by 9–167.0%
Dolphins by 17+2.5%

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 +6.9 points to the Dolphins: the final margin was Dolphins by 9, without the luck Dolphins by 2.1. 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.

  • J. Sanders, 30 yds made · 96% expected
  • N. Folk, 43 yds made · 83% expected
  • J. Sanders, 49 yds made · 70% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Patriots 8 for 78 yards, Dolphins 5 for 33 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 11:36 Encroachment on the Patriots (Carl Davis), 5 yards · pre-snap +2% MIA +0.5 pts
Q1 6:07 Defensive Too Many Men on Field on the Dolphins, 5 yards · pre-snap +1% NE +0.7 pts
Q1 0:53 Unnecessary Roughness on the Patriots (Brandon Bolden), 15 yards +2% MIA +1.3 pts
Q2 4:23 False Start on the Dolphins, 5 yards · pre-snap +1% NE +0.5 pts
Q2 1:08 False Start on the Patriots (Mac Jones), 4 yards · pre-snap +1% MIA +0.3 pts
Q2 0:26 Roughing the Passer on the Patriots (Matt Judon), 15 yards +1% MIA +0.4 pts
Q3 12:46 Defensive Pass Interference on the Dolphins (Eric Rowe), 7 yards +5% NE +1.5 pts
Q3 6:03 Defensive Offside on the Patriots (Deatrich Wise Jr.), 4 yards · pre-snap +2% MIA +0.5 pts
Q3 4:42 Defensive Pass Interference on the Patriots (Jalen Mills), 24 yards +5% MIA +3.5 pts
Q3 0:07 Illegal Formation on the Patriots (Lawrence Guy), 6 yards · pre-snap +2% MIA +3.4 pts
Q4 7:19 False Start on the Patriots (Kendrick Bourne), 5 yards · pre-snap 0% MIA +0.5 pts
Q4 3:02 Defensive Pass Interference on the Dolphins (Byron Jones), 11 yards +5% NE +1.7 pts
Q4 0:14 Delay of Game on the Dolphins, 5 yards · pre-snap +1% MIA +0.1 pts

Patriots penalties, every game · Dolphins penalties, every game · All teams, 2021

When it happened

Dolphins’ chance of winning

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 Patriots were.
#WhenWhat happenedWin probability forNext drive
1 Q1 6:16 The Patriots were stopped on 3rd & 13rd & 4th downs · 74% expectedReturn touchdown by the DolphinsSpecial teams +30% MIA NE: Punt
2 Q3 12:46 Defensive Pass Interference on the Dolphins (Eric Rowe), 7 yardsJudgment calls · 10 flags in 2692 snaps before, position avg 1 per 420 +5% NE NE: Field goal
3 Q3 9:08 The Patriots were stopped on 3rd & 43rd & 4th downs · 45% expected +7% MIA NE: Field goal
4 Q3 4:42 Defensive Pass Interference on the Patriots (Jalen Mills), 24 yardsJudgment calls · 9 flags in 2519 snaps before, position avg 1 per 213 +5% MIA MIA: Touchdown
5 Q3 2:29 The Patriots fumbled and the Dolphins recoveredFumble bounces · loose balls are close to 50/50 +5% MIA NE: Touchdown
6 Q4 3:02 Defensive Pass Interference on the Dolphins (Byron Jones), 11 yardsJudgment calls · 7 flags in 2886 snaps before, position avg 1 per 213 +5% NE NE: Touchdown
7 Q4 1:56 The Dolphins converted 3rd & 83rd & 4th downs · 30% expected +8% MIA MIA: Punt
8 Q4 0:03 The Patriots fumbled and the Dolphins recoveredFumble bounces · loose balls are close to 50/50Return touchdown by the DolphinsSpecial teams +7% MIA –

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.

  • Kyle Dugger (NE FS), out · 0.4 pts
  • Dont'a Hightower (NE LB), out · 0.4 pts
  • Myles Bryant (NE CB), 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

Patriots 32% · Dolphins 68%

Final margin
Dolphins by 9
Luck in points
6.9 for the Dolphins
Luck-adjusted margin
Dolphins by 2.1
Replay with same day's form
Patriots 72% · Dolphins 28% 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 18 2021 games · Patriots · Dolphins

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