luckadjusted

Week 18 2021 · January 9, 2022

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

Seahawks at Cardinals, Week 18 2021: who deserved to win?

The Seahawks beat the Cardinals 38–30, and it was no fluke: replayed with the way both teams actually played, the Seahawks win 8 of 10. The Cardinals had the bounces: fumble bounces alone were worth 3.1 points to the Cardinals.

An off day for the Cardinals: their offense and defense both played far below their usual level. In a fresh game against the Seahawks they would win 60% of the time; with this day’s form, 17%. The numbers

Before kickoff the Cardinals were 66% favorites. The biggest swing (Q1, 14:55 left): Return touchdown by the Cardinals, worth 25 points of win probability to the Cardinals.

Final

Seattle Seahawks 38
Arizona Cardinals 30

January 9, 2022 · State Farm Stadium · Closing line: Cardinals −5.5

Luck index +17 Seahawks about even · −17 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. Seahawks win 8, Cardinals win 2.

  1. 1 SEA 36 ARI 6
  2. 2 SEA 33 ARI 10
  3. 3 SEA 41 ARI 23
  4. 4 SEA 21 ARI 7
  5. 5 SEA 27 ARI 17
  6. 6 SEA 22 ARI 14
  7. 7 SEA 24 ARI 20
  8. 8 SEA 12 ARI 10
  9. 9 SEA 17 ARI 20
  10. 10 SEA 20 ARI 31

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 Cardinals

Their offense and defense both played far below their usual level. In a fresh game against the Seahawks they would win 60% of the time; with this day’s form, 17%.

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

UnitThis gameUsual levelBetter or worse than usual
Seahawks offenseEPA per play gained +0.46 +0.12 better by 0.34
Seahawks defenseEPA per play allowed −0.01 +0.10 better by 0.12
Cardinals offenseEPA per play gained −0.01 +0.16 worse by 0.18
Cardinals defenseEPA per play allowed +0.46 +0.11 worse by 0.35

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

Seahawks win 83% of them, Cardinals 17%, counting the 1% still level after regulation as half each. The line is what actually happened: Seahawks by 8.

Show as a table
Final margin in the replaysShare of replays
Seahawks by 17+35.9%
Seahawks by 9–1622.1%
Seahawks by 1–824.9%
Level after regulation1.3%
Cardinals by 1–810.3%
Cardinals by 9–164.0%
Cardinals by 17+1.5%

Where the luck was

Take the luck out

The final margin was Seahawks by 8. Remove the luck, one kind at a time, and it becomes Seahawks by 7.0.

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.

  • M. Prater, 41 yds made · 84% expected
  • J. Myers, 38 yds made · 89% expected
  • M. Prater, 30 yds made · 95% expected
  • M. Prater, 36 yds made · 91% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Cardinals’ chance of winning

As low as 0% and as high as 81%. 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 Cardinals were ahead in it, below while the Seahawks were.
#WhenWhat happenedWin probability forNext drive
1 Q1 14:55 The Seahawks fumbled and the Cardinals recoveredFumble bounces · loose balls are close to 50/50Return touchdown by the CardinalsSpecial teams +25% ARI SEA: Touchdown
2 Q1 12:34 The Seahawks converted 3rd & 23rd & 4th downs · 58% expected +13% SEA SEA: Touchdown
3 Q1 6:33 Offensive Pass Interference on the Cardinals (A.J. Green), 6 yards, wiping out the playJudgment calls · 6 flags in 1642 snaps before, position avg 1 per 399 +9% SEA SEA: Touchdown
4 Q1 0:39 Neutral Zone Infraction on the Seahawks (Rasheem Green), 5 yardsPre-snap flags · 3 flags in 1984 snaps before, position avg 1 per 266 +9% ARI ARI: Field goal
5 Q2 9:52 The Seahawks converted 3rd & 83rd & 4th downs · 29% expected +12% SEA SEA: Touchdown
6 Q2 7:41 Illegal Shift on the Cardinals (Christian Kirk), 5 yards, wiping out the playPre-snap flags · 2 flags in 2487 snaps before, position avg 1 per 399 +13% SEA SEA: Field goal
7 Q3 10:12 The Seahawks were stopped on 3rd & 73rd & 4th downs · 32% expected +15% ARI SEA: Punt
8 Q4 13:22 The Seahawks converted 3rd & 43rd & 4th downs · 36% expected +20% SEA SEA: 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.

  • DeAndre Hopkins (ARI WR), out (IR) · 1.1 pts
  • Marco Wilson (ARI CB), out · 0.5 pts
  • Robert Alford (ARI CB), out (IR) · 0.4 pts
  • Jordan Phillips (ARI DE), out · 0.3 pts
  • Chase Edmonds (ARI RB), out · 0.1 pts
  • Bobby Wagner (SEA LB), out · 0.8 pts
  • Brandon Shell (SEA T), out (IR) · 0.7 pts
  • Jamal Adams (SEA SS), out (IR) · 0.7 pts
  • Gabe Jackson (SEA G), out · 0.4 pts
  • Ryan Neal (SEA SS), out (IR) · 0.3 pts
  • Tre Brown (SEA DB), out (IR) · 0.2 pts
  • Al Woods (SEA DT), out (IR) · 0.2 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

Seahawks 83% · Cardinals 17%

Final margin
Seahawks by 8
Luck in points
1.0 for the Seahawks
Luck-adjusted margin
Seahawks by 7.0
Replay with same day's form
Seahawks 83% · Cardinals 17% 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 · Seahawks · Cardinals

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