luckadjusted

Week 4 2021 · October 3, 2021

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

Colts at Dolphins, Week 4 2021: who deserved to win?

The Colts beat the Dolphins 27–17, and it was no fluke: replayed with the way both teams actually played, the Colts win 9 of 10. The Dolphins had the bounces: injuries alone were worth 4.4 points to the Dolphins.

An off day for the Dolphins: their offense played far below its usual level. In a fresh game against the Colts they would win 45% of the time; with this day’s form, 12%. The numbers

Before kickoff the Dolphins were 57% favorites. The biggest swing (Q1, 11:58 left): Illegal Use of Hands on the Dolphins, 10 yards, wiping out the play, worth 11 points of win probability to the Colts.

Final

Indianapolis Colts 27
Miami Dolphins 17

October 3, 2021 · Hard Rock Stadium · Closing line: Dolphins −2.5

Luck index +12 Colts about even · −12 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. Colts win 9, Dolphins win 1.

  1. 1 IND 37 MIA 9
  2. 2 IND 31 MIA 10
  3. 3 IND 30 MIA 13
  4. 4 IND 34 MIA 20
  5. 5 IND 32 MIA 20
  6. 6 IND 27 MIA 17
  7. 7 IND 17 MIA 10
  8. 8 IND 22 MIA 17
  9. 9 IND 13 MIA 10
  10. 10 IND 10 MIA 17

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 Dolphins

Their offense played far below its usual level. In a fresh game against the Colts they would win 45% of the time; with this day’s form, 12%.

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

UnitThis gameUsual levelBetter or worse than usual
Colts offenseEPA per play gained +0.20 +0.12 better by 0.08
Colts defenseEPA per play allowed −0.27 +0.15 better by 0.42
Dolphins offenseEPA per play gained −0.27 +0.08 worse by 0.35
Dolphins defenseEPA per play allowed +0.20 +0.14 worse by 0.06

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

Colts win 88% of them, Dolphins 12%, counting the 2% still level after regulation as half each. The line is what actually happened: Colts by 10.

Show as a table
Final margin in the replaysShare of replays
Colts by 17+45.5%
Colts by 9–1624.1%
Colts by 1–818.0%
Level after regulation2.1%
Dolphins by 1–87.1%
Dolphins by 9–162.8%
Dolphins by 17+0.3%

Where the luck was

Take the luck out

The final margin was Colts by 10. Remove the luck, one kind at a time, and it becomes Colts by 13.0.

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.

  • J. Sanders, 38 yds made · 87% expected
  • R. Blankenship, 34 yds made · 91% expected
  • R. Blankenship, 43 yds made · 79% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Dolphins’ chance of winning

As low as 0% and as high as 71%. 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 Colts were.
#WhenWhat happenedWin probability forNext drive
1 Q1 11:58 Illegal Use of Hands on the Dolphins, 10 yards, wiping out the playJudgment calls +11% IND IND: Punt
2 Q1 11:21 The Colts fumbled and the Dolphins recoveredFumble bounces · loose balls are close to 50/50 +8% MIA IND: Punt
3 Q1 10:49 The Dolphins fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +6% MIA MIA: Field goal
4 Q2 10:54 Offensive Holding on the Colts (Zach Pascal), 10 yards, wiping out the playJudgment calls · 6 flags in 2043 snaps before, position avg 1 per 399 +8% MIA MIA: Punt
5 Q2 9:39 The Colts were stopped on 3rd & 73rd & 4th downs · 33% expected +6% MIA IND: Punt
6 Q2 4:45 Defensive Offside on the Dolphins, 5 yardsPre-snap flags +6% IND IND: Touchdown
7 Q3 10:34 The Colts converted 3rd & 63rd & 4th downs · 29% expectedNeutral Zone Infraction on the Dolphins (Jaelan Phillips), 5 yardsPre-snap flags · 0 flags in 104 snaps before, position avg 1 per 409 +10% IND IND: Touchdown
8 Q4 10:46 The Dolphins converted 4th & 13rd & 4th downs · 64% expected +7% 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.

  • Raekwon Davis (MIA DT), out (IR) · 0.4 pts
  • Michael Deiter (MIA C), out (IR) · 0.3 pts
  • T.Y. Hilton (IND WR), out (IR) · 0.9 pts
  • Quenton Nelson (IND G), out (IR) · 0.8 pts
  • Kwity Paye (IND DE), out · 0.7 pts
  • Quenton Nelson (IND G/C), out (IR) · 0.6 pts
  • Khari Willis (IND SS), out · 0.5 pts
  • Khari Willis (IND S), out · 0.5 pts
  • Braden Smith (IND T/G), out · 0.4 pts
  • T.J. Carrie (IND CB), out (IR) · 0.4 pts
  • Rock Ya-Sin (IND CB), 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

Colts 86% · Dolphins 14%

Final margin
Colts by 10
Luck in points
3.0 for the Dolphins
Luck-adjusted margin
Colts by 13.0
Replay with same day's form
Colts 88% · Dolphins 12% 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 4 2021 games · Colts · Dolphins

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