luckadjusted
NFL Week 9 · 2026

Week 1 2021 · September 12, 2021

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

Dolphins at Patriots, Week 1 2021: who deserved to win?

The Dolphins beat the Patriots 17–16, and the replays lean their way: with the same day's form, they win 8 of 10.

An off day for the Patriots: they played far below what the matchup promised. In a fresh game against the Dolphins they would win 59% of the time; with this day’s form, 22%. The numbers

Before kickoff the Patriots were 60% favorites. The game turned on a luck play (Q4, 3:35 left): the Patriots fumbled and the Dolphins recovered, worth 18 points of win probability to the Dolphins.

Final

Miami Dolphins 17
New England Patriots 16

September 12, 2021 · Gillette Stadium · Closing line: Patriots −3.5

Luck index +22 Dolphins about even · −22 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. Dolphins win 8, Patriots win 2.

  1. 1 MIA 37 NE 10
  2. 2 MIA 30 NE 10
  3. 3 MIA 16 NE 0
  4. 4 MIA 41 NE 28
  5. 5 MIA 33 NE 23
  6. 6 MIA 24 NE 16
  7. 7 MIA 33 NE 28
  8. 8 MIA 16 NE 13
  9. 9 MIA 20 NE 24
  10. 10 MIA 10 NE 24

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.

An off day for the Patriots

They played far below what the matchup promised. In a fresh game against the Dolphins they would win 59% of the time; with this day’s form, 22%.

37 points apart for the Patriots: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Dolphins offenseEPA per play gained +0.11 +0.12 worse by 0.01
Dolphins defenseEPA per play allowed +0.17 +0.12 worse by 0.05
Patriots offenseEPA per play gained +0.17 +0.14 better by 0.04
Patriots defenseEPA per play allowed +0.11 +0.18 better by 0.07

EPA (expected points added) per play on competitive snaps, turnovers left out because they are valued as luck. Usual level: the team’s earlier games this season plus half of last season, pulled toward the league average. One team’s defense and the other team’s offense are the same snaps, so one game can’t fully say whose day it was; it shows how far this one was from both teams’ norms.

How 4,000 replays ended

Dolphins win 78% of them, Patriots 22%, counting the 3% still level after regulation as half each. The line is what actually happened: Dolphins by 1.

Show as a table
Final margin in the replaysShare of replays
Dolphins by 17+26.8%
Dolphins by 9–1622.4%
Dolphins by 1–828.5%
Level after regulation2.9%
Patriots by 1–811.2%
Patriots by 9–165.9%
Patriots by 17+2.4%

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 +1.6 points to the Dolphins: the final margin was Dolphins by 1, without the luck Patriots by 0.6. 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.

  • N. Folk, 27 yds made · 97% expected
  • J. Sanders, 48 yds made · 70% expected
  • N. Folk, 42 yds made · 83% expected
  • N. Folk, 33 yds made · 93% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Dolphins 5 for 28 yards, Patriots 8 for 84 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 half toward luck; pre-snap fouls, which repeat, don’t count. How calls are valued

WhenFlagWin probability for
Q1 5:35 Unnecessary Roughness on the Patriots (Deatrich Wise Jr.), 15 yards +4% MIA +1.1 pts
Q2 12:09 Offensive Holding on the Patriots, 10 yards, wiping out the play +7% MIA +2.2 pts
Q2 3:36 Roughing the Passer on the Dolphins (Elandon Roberts), 9 yards, wiping out the play +8% NE +2.0 pts
Q2 2:16 Neutral Zone Infraction on the Patriots (Kyle Van Noy), 5 yards · pre-snap +3% MIA +0.6 pts
Q2 0:56 False Start on the Dolphins, 5 yards · pre-snap +3% NE +0.6 pts
Q3 10:51 Offensive Holding on the Patriots, 9 yards +1% MIA +0.8 pts
Q3 8:33 Illegal Formation on the Patriots, 5 yards · pre-snap +3% MIA +1.2 pts
Q3 7:36 Offensive Holding on the Patriots, 10 yards, wiping out the play +15% MIA +3.9 pts
Q3 7:07 Illegal Use of Hands on the Dolphins (Zach Sieler), 5 yards, wiping out the play +3% MIA +0.4 pts
Q3 1:27 Unnecessary Roughness on the Patriots (Matt Judon), 15 yards +8% MIA +0.8 pts
Q3 1:13 Illegal Blindside Block on the Patriots, 15 yards +1% MIA +1.4 pts
Q4 8:47 Ineligible Downfield Pass on the Dolphins, 5 yards +7% NE +1.0 pts
Q4 3:31 Offensive Holding on the Dolphins, 4 yards, wiping out the play +12% NE +1.2 pts

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

When it happened

Patriots’ chance of winning

As low as 0% and as high as 74%. 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 Patriots were ahead in it, below while the Dolphins were.
#WhenWhat happenedWin probability forNext drive
1 Q2 3:36 Roughing the Passer on the Dolphins (Elandon Roberts), 9 yards, wiping out the playJudgment calls · 2 flags in 881 snaps before, position avg 1 per 409 +8% NE NE: Touchdown
2 Q2 0:27 The Dolphins were stopped on 3rd & 53rd & 4th downs · 43% expected +9% NE MIA: Field goal
3 Q3 7:36 Offensive Holding on the Patriots, 10 yards, wiping out the playJudgment calls +15% MIA MIA: Punt
4 Q3 5:55 The Patriots converted 3rd & 113rd & 4th downs · 26% expected +8% NE NE: Field goal
5 Q4 12:22 The Patriots converted 3rd & 73rd & 4th downs · 34% expected +10% NE NE: Field goal
6 Q4 3:35 The game turned hereThe Patriots fumbled and the Dolphins recoveredFumble bounces · loose balls are close to 50/50 +18% MIA –
7 Q4 3:31 Offensive Holding on the Dolphins, 4 yards, wiping out the playJudgment calls +12% NE –
8 Q4 2:24 The Dolphins converted 3rd & 13rd & 4th downs · 75% expected +12% MIA MIA: 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.

  • Stephon Gilmore (NE CB), out (IR) · 1.1 pts
  • N'Keal Harry (NE WR), out (IR) · 0.3 pts
  • Devin Asiasi (NE TE), out · 0.2 pts
  • Austin Jackson (MIA T), out · 0.6 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

Dolphins 50% · Patriots 50%

Final margin
Dolphins by 1
Luck in points
1.6 for the Dolphins
Luck-adjusted margin
Patriots by 0.6
Replay with same day's form
Dolphins 78% · Patriots 22% unchanged: why
How much of each is luck?

0% treats it as skill, 100% as pure luck. The tick is our fit.

What counts

None by default: our tests measured no carryover after a lucky break. Slide it up to count a break for more than its own swing. 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 1 2021 games · Dolphins · Patriots

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