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 11 points of win probability 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 |
Replay with same day's form
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 SEA 36 ARI 6
- 2 SEA 37 ARI 14
- 3 SEA 34 ARI 16
- 4 SEA 21 ARI 7
- 5 SEA 30 ARI 20
- 6 SEA 25 ARI 17
- 7 SEA 17 ARI 13
- 8 SEA 19 ARI 17
- 9 SEA 17 ARI 20
- 10 SEA 17 ARI 28
Three other ways to ask
Each answers a different question, so none of them replaces the replay above.
Before kickoff
The closing betting line, turned into a probability. What everyone knew before the game.
Same teams, fresh 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.
Only coin-flips re-rolled
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%.
Same teams, fresh game
Replay with same day's form
44 points apart for the Cardinals: the gap is how differently this game went from what the two teams usually are.
| Unit | This game | Usual level | Better 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 replays | Share of replays |
|---|---|
| Seahawks by 17+ | 35.9% |
| Seahawks by 9–16 | 22.1% |
| Seahawks by 1–8 | 24.9% |
| Level after regulation | 1.3% |
| Cardinals by 1–8 | 10.3% |
| Cardinals by 9–16 | 4.0% |
| Cardinals by 17+ | 1.5% |
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.
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
Penalties: Seahawks 4 for 30 yards, Cardinals 6 for 46 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
| When | Flag | Win probability for |
|---|---|---|
| Q1 11:25 | Neutral Zone Infraction on the Seahawks (Darrell Taylor), 5 yards · pre-snap | +3% ARI +1.1 pts |
| Q1 6:33 | Offensive Pass Interference on the Cardinals (A.J. Green), 6 yards, wiping out the play | +9% SEA +2.8 pts |
| Q1 0:39 | Neutral Zone Infraction on the Seahawks (Rasheem Green), 5 yards · pre-snap | +9% ARI +3.9 pts |
| Q2 7:41 | Illegal Shift on the Cardinals (Christian Kirk), 5 yards, wiping out the play · pre-snap | +13% SEA +5.3 pts |
| Q2 4:34 | Offensive Holding on the Cardinals, 10 yards, wiping out the play | +6% SEA +1.5 pts |
| Q2 3:57 | Delay of Game on the Cardinals, 5 yards · pre-snap | 0% SEA +0.4 pts |
| Q2 1:52 | Offensive Pass Interference on the Seahawks (Gerald Everett), 10 yards, wiping out the play | +7% ARI +2.4 pts |
| Q3 14:56 | Offensive Holding on the Cardinals, 10 yards | +3% SEA +1.4 pts |
| Q3 4:48 | Illegal Block Above the Waist on the Seahawks, 10 yards | +4% ARI +0.9 pts |
| Q4 1:24 | Offensive Pass Interference on the Cardinals (Zach Ertz), 10 yards | 0% SEA +0.9 pts |
Seahawks penalties, every game · Cardinals penalties, every game · All teams, 2021
When it happened
Cardinals’ chance of winning
As low as 0% and as high as 81%. Numbers mark the biggest luck moments, listed below.
| # | When | What happened | Win probability for | Next 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
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
More from Week 18 2021
- Chiefs at Broncos KC 28–24 · replay 79% for the winner
- Cowboys at Eagles DAL 51–26 · replay 94% for the winner
- Bears at Vikings MIN 31–17 · replay 54% for the winner
- Bengals at Browns CLE 21–16 · replay 89% for the winner
- Packers at Lions DET 37–30 · replay 53% for the winner
- Colts at Jaguars JAX 26–11 · replay 82% for the winner
- Steelers at Ravens PIT 16–13 · replay 17% for the winner
- Titans at Texans TEN 28–25 · replay 71% for the winner
- Washington at Giants WAS 22–7 · replay 92% for the winner
- Panthers at Buccaneers TB 41–17 · replay 99% for the winner
- Patriots at Dolphins MIA 33–24 · replay 28% for the winner
- Saints at Falcons NO 30–20 · replay 77% for the winner
- Jets at Bills BUF 27–10 · replay 100% for the winner
- 49ers at Rams SF 27–24 · replay 75% for the winner
- Chargers at Raiders LV 35–32 · replay 58% for the winner