luckadjusted

Week 13 2021 · December 5, 2021

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

Giants at Dolphins, Week 13 2021: who deserved to win?

The Dolphins beat the Giants 20–9 and were the better team on the day: replayed with the same form, they win 7 of 10.

Before kickoff the Dolphins were 68% favorites.

Final

New York Giants 9
Miami Dolphins 20

December 5, 2021 · Hard Rock Stadium · Closing line: Dolphins −6.5

Luck index +29 Dolphins lucky · −29 Giants

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. Giants win 3, Dolphins win 7.

  1. 1 NYG 21 MIA 6
  2. 2 NYG 28 MIA 20
  3. 3 NYG 15 MIA 13
  4. 4 NYG 13 MIA 15
  5. 5 NYG 17 MIA 23
  6. 6 NYG 13 MIA 22
  7. 7 NYG 17 MIA 29
  8. 8 NYG 0 MIA 15
  9. 9 NYG 10 MIA 29
  10. 10 NYG 6 MIA 32

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

Giants win 29% of them, Dolphins 71%, counting the 4% still level after regulation as half each. The line is what actually happened: Dolphins by 11.

Show as a table
Final margin in the replaysShare of replays
Giants by 17+2.9%
Giants by 9–168.7%
Giants by 1–814.1%
Level after regulation3.8%
Dolphins by 1–826.5%
Dolphins by 9–1621.4%
Dolphins by 17+22.6%

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 +1.9 points to the Dolphins: the final margin was Dolphins by 11, without the luck Dolphins by 9.1. 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.

  • G. Gano, 39 yds made · 88% expected
  • J. Sanders, 48 yds made · 72% expected
  • G. Gano, 34 yds made · 94% expected
  • J. Sanders, 52 yds missed · 65% expected
  • G. Gano, 51 yds made · 71% expected
  • J. Sanders, 48 yds made · 71% expected
  • G. Gano, 56 yds missed · 63% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Giants 3 for 23 yards, Dolphins 3 for 15 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 2:01 Defensive Offside on the Giants (Leonard Williams), 5 yards · pre-snap +1% NYG +0.2 pts
Q3 7:18 False Start on the Dolphins, 5 yards · pre-snap +1% NYG +1.0 pts
Q3 0:27 Delay of Game on the Giants, 3 yards · pre-snap 0% MIA +0.1 pts
Q4 10:20 Unsportsmanlike Conduct on the Giants (Keion Crossen), 15 yards 0% MIA +1.3 pts
Q4 1:16 False Start on the Dolphins (Zach Sieler), 5 yards · pre-snap 0% NYG +0.3 pts
Q4 0:49 Defensive Offside on the Dolphins (Andrew Van Ginkel), 5 yards · pre-snap 0% NYG +0.4 pts

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

When it happened

Dolphins’ chance of winning

As low as 44% and as high as 100%. 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 Giants were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:38 The Giants converted 3rd & 43rd & 4th downs · 42% expected +5% NYG NYG: Punt
2 Q1 4:52 The Giants converted 3rd & 113rd & 4th downs · 23% expected +8% NYG NYG: Turnover
3 Q2 15:00 The Giants converted 3rd & 63rd & 4th downs · 34% expected +6% NYG NYG: Field goal
4 Q2 13:21 The Giants were stopped on 3rd & 103rd & 4th downs · 25% expected +5% MIA NYG: Field goal
5 Q2 6:19 The Giants converted 3rd & 93rd & 4th downs · 27% expected +6% NYG NYG: Punt
6 Q3 12:31 The Giants converted 3rd & 103rd & 4th downs · 25% expected +7% NYG NYG: Field goal
7 Q3 2:46 The Giants converted 3rd & 73rd & 4th downs · 31% expected +5% NYG NYG: Punt
8 Q4 11:13 The Dolphins converted 3rd & 23rd & 4th downs · 52% expected +5% MIA MIA: 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.

  • Brandon Jones (MIA SS), out · 0.3 pts
  • Greg Mancz (MIA C), out (IR) · 0.2 pts
  • Adam Shaheen (MIA TE), out · 0.2 pts
  • Daniel Jones (NYG QB), out, replaced by m.glennon · 1.6 pts
  • Adoree' Jackson (NYG CB), out · 0.7 pts
  • Sterling Shepard (NYG WR), out · 0.4 pts
  • Kadarius Toney (NYG WR), out · 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

Giants 2% · Dolphins 98%

Final margin
Dolphins by 11
Luck in points
1.9 for the Dolphins
Luck-adjusted margin
Dolphins by 9.1
Replay with same day's form
Giants 29% · Dolphins 71% 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 13 2021 games · Giants · Dolphins

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