luckadjusted

Week 15 2021 · December 19, 2021

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

Cardinals at Lions, Week 15 2021: who deserved to win?

The Lions stole one. They beat the Cardinals 30–12, but replayed with the way both teams actually played, the Cardinals win 8 of 10. Luck ran their way: judgment calls alone were worth 3.7 points to the Lions.

Before kickoff the Cardinals were 83% favorites.

Final

Arizona Cardinals 12
Detroit Lions 30

December 19, 2021 · Ford Field · Closing line: Cardinals −13

Luck index +80 Lions very lucky · −80 Cardinals

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. Cardinals win 8, Lions win 2.

  1. 1 ARI 41 DET 13
  2. 2 ARI 37 DET 17
  3. 3 ARI 29 DET 13
  4. 4 ARI 33 DET 20
  5. 5 ARI 10 DET 0
  6. 6 ARI 24 DET 17
  7. 7 ARI 24 DET 20
  8. 8 ARI 36 DET 34
  9. 9 ARI 27 DET 30
  10. 10 ARI 22 DET 33

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

Cardinals win 80% of them, Lions 20%, counting the 3% still level after regulation as half each. The line is what actually happened: Lions by 18.

Show as a table
Final margin in the replaysShare of replays
Cardinals by 17+32.2%
Cardinals by 9–1620.4%
Cardinals by 1–826.3%
Level after regulation2.5%
Lions by 1–811.5%
Lions by 9–165.5%
Lions by 17+1.6%

Where the luck was

Take the luck out

The final margin was Lions by 18. Remove the luck, one kind at a time, and it becomes Lions by 13.9.

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.

  • R. Patterson, 37 yds made · 92% expected
  • M. Prater, 29 yds made · 97% expected
  • M. Prater, 29 yds made · 97% expected
  • R. Patterson, 47 yds made · 80% expected
  • R. Patterson, 45 yds made · 83% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Lions’ chance of winning

As low as 50% 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 Lions were ahead in it, below while the Cardinals were.
#WhenWhat happenedWin probability forNext drive
1 Q1 11:26 The Lions converted 3rd & 53rd & 4th downs · 38% expected +4% DET DET: Field goal
2 Q1 2:55 The Lions converted 3rd & 53rd & 4th downs · 38% expected +5% DET DET: Touchdown
3 Q1 0:50 The Lions converted 3rd & 53rd & 4th downs · 38% expected +7% DET DET: Touchdown
4 Q2 14:09 The Cardinals were stopped on 3rd & 43rd & 4th downs · 47% expected +4% DET ARI: Punt
5 Q2 8:29 The Cardinals were stopped on 3rd & 33rd & 4th downs · 53% expected +4% DET ARI: Punt
6 Q2 2:02 The Cardinals were stopped on 4th & 33rd & 4th downs · 44% expected +7% DET ARI: End of half
7 Q2 1:53 Roughing the Passer on the Cardinals (Chandler Jones), 15 yardsJudgment calls · 8 flags in 1988 snaps before, position avg 1 per 409 +5% DET DET: Touchdown
8 Q2 0:31 The Lions converted 4th & 13rd & 4th downs · 70% expected +4% DET DET: 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.

  • T.J. Hockenson (DET TE), out (IR) · 1.0 pts
  • Jerry Jacobs (DET CB), out (IR) · 0.6 pts
  • Trinity Benson (DET WR), out · 0.5 pts
  • D'Andre Swift (DET RB), out · 0.4 pts
  • Jonah Jackson (DET G), out · 0.4 pts
  • Tracy Walker (DET FS), out · 0.3 pts
  • Trey Flowers (DET LB), out (IR) · 0.3 pts
  • Austin Seibert (DET K), out (IR) · 0.2 pts
  • Julian Okwara (DET LB), out · 0.1 pts
  • J.J. Watt (ARI DE), out (IR) · 1.1 pts
  • DeAndre Hopkins (ARI WR), out (IR) · 1.1 pts
  • Rodney Hudson (ARI C), out (IR) · 0.6 pts
  • Robert Alford (ARI CB), out (IR) · 0.4 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

Cardinals 1% · Lions 99%

Final margin
Lions by 18
Luck in points
4.1 for the Lions
Luck-adjusted margin
Lions by 13.9
Replay with same day's form
Cardinals 80% · Lions 20% 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 15 2021 games · Cardinals · Lions

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