luckadjusted

Week 18 2023 · January 7, 2024

Seahawks at Cardinals, Week 18 2023: who deserved to win?

The Seahawks beat the Cardinals 21–20, but it was a coin flip: replayed with the way both teams played, the Seahawks win 4 of 10. Luck ran their way: kicks alone were worth 56 points of win probability to the Seahawks.

Before kickoff the Seahawks were 57% favorites. The game turned on a luck play (Q4, 0:01 left): M. Prater missed 51-yard field goal, worth 55 points of win probability to the Seahawks.

Final

Seattle Seahawks 21
Arizona Cardinals 20

January 7, 2024 · State Farm Stadium · Closing line: Seahawks −2.5

Luck index +57 Seahawks lucky · −57 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 4, Cardinals win 6.

  1. 1 SEA 23 ARI 7
  2. 2 SEA 24 ARI 15
  3. 3 SEA 31 ARI 27
  4. 4 SEA 22 ARI 20
  5. 5 SEA 24 ARI 26
  6. 6 SEA 17 ARI 20
  7. 7 SEA 10 ARI 17
  8. 8 SEA 7 ARI 17
  9. 9 SEA 20 ARI 34
  10. 10 SEA 17 ARI 37

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

Seahawks win 43% of them, Cardinals 57%, counting the 7% still level after regulation as half each. The line is what actually happened: Seahawks by 1.

Show as a table
Final margin in the replaysShare of replays
Seahawks by 17+6.2%
Seahawks by 9–1613.1%
Seahawks by 1–823.4%
Level after regulation6.9%
Cardinals by 1–824.2%
Cardinals by 9–1616.4%
Cardinals by 17+9.8%

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 +8.1 points to the Seahawks: the final margin was Seahawks by 1, without the luck Cardinals by 7.2. 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.

  • J. Myers, 33 yds made · 95% expected
  • M. Prater, 23 yds made · 99% expected
  • M. Prater, 34 yds made · 95% expected
  • J. Myers, 29 yds made · 97% expected
  • M. Prater, 43 yds missed · 85% expected
  • M. Prater, 51 yds missed · 75% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Seahawks 0 for 0 yards, Cardinals 5 for 27 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
Q1 11:09 False Start on the Cardinals, 5 yards · pre-snap +1% SEA +0.8 pts
Q2 6:18 Offensive Offside on the Cardinals (Michael Wilson), 4 yards · pre-snap +3% SEA +1.2 pts
Q2 2:19 False Start on the Cardinals (Trey McBride), 5 yards · pre-snap +2% SEA +0.5 pts
Q2 0:59 Defensive Pass Interference on the Cardinals, 8 yards, wiping out the play +3% ARI +0.6 pts
Q4 10:25 False Start on the Cardinals, 5 yards · pre-snap +2% SEA +0.6 pts

Seahawks penalties, every game · Cardinals penalties, every game · All teams, 2023

When it happened

Cardinals’ chance of winning

As low as 0% and as high as 95%. 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 Q2 11:54 The Cardinals were stopped on 3rd & 23rd & 4th downs · 54% expected +9% SEA ARI: Field goal
2 Q2 8:33 The Seahawks converted 3rd & 83rd & 4th downs · 31% expected +16% SEA SEA: Touchdown
3 Q4 15:00 The Cardinals converted 3rd & 103rd & 4th downs · 29% expected +12% ARI ARI: Touchdown
4 Q4 9:52 The Cardinals converted 4th & 33rd & 4th downs · 45% expected +19% ARI ARI: Touchdown
5 Q4 3:00 M. Prater missed 43-yard field goalKicks · 85% expected for him +6% SEA ARI: Missed field goal
6 Q4 1:54 The Seahawks’ two-point try was good3rd & 4th downs · 47% expectedR. Moore dropped a catchable passDrops · 8 drops on 95 catchable balls before this +42% SEA SEA: Missed field goal
7 Q4 0:46 The Cardinals converted 3rd & 83rd & 4th downs · 33% expected +23% ARI ARI: Missed field goal
8 Q4 0:01 The game turned hereM. Prater missed 51-yard field goalKicks · 75% expected for him, 46 of 63 from 45+ before +55% SEA –

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.

  • Marquise Brown (ARI WR), out (IR) · 0.9 pts
  • D.J. Humphries (ARI T), out (IR) · 0.7 pts
  • Divaad Wilson (ARI CB), out · 0.5 pts
  • Garrett Williams (ARI CB), out · 0.5 pts
  • Kyzir White (ARI LB), out (IR) · 0.4 pts
  • Jonathan Ledbetter (ARI DE), out (IR) · 0.4 pts
  • Carter O'Donnell (ARI T), out · 0.4 pts
  • Dante Stills (ARI DE), out (IR) · 0.3 pts
  • Josh Woods (ARI LB), out (IR) · 0.3 pts
  • Dennis Daley (ARI T), out · 0.3 pts
  • Abraham Lucas (SEA T), out · 0.8 pts
  • Jamal Adams (SEA SS), out (IR) · 0.7 pts
  • Jarran Reed (SEA NT), out · 0.3 pts
  • Phil Haynes (SEA G), 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 15% · Cardinals 85%

Final margin
Seahawks by 1
Luck in points
8.1 for the Seahawks
Luck-adjusted margin
Cardinals by 7.1
Replay with same day's form
Seahawks 43% · Cardinals 57% 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; injuries from snap counts and injury reports.

Methodology and validation · All Week 18 2023 games · Seahawks · Cardinals

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