luckadjusted

Week 18 2024 · January 5, 2025

49ers at Cardinals, Week 18 2024: who deserved to win?

The Cardinals beat the 49ers 47–24, and it was no fluke: replayed with the way both teams actually played, the Cardinals win 8 of 10.

Before kickoff the Cardinals were 63% favorites. The biggest swing (Q1, 2:33 left): the Cardinals converted 4th & 4, worth 13 points of win probability to the Cardinals.

Final

San Francisco 49ers 24
Arizona Cardinals 47

January 5, 2025 · State Farm Stadium · Closing line: Cardinals −4.5

Luck index +19 Cardinals about even · −19 49ers

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. 49ers win 2, Cardinals win 8.

  1. 1 SF 44 ARI 27
  2. 2 SF 36 ARI 32
  3. 3 SF 35 ARI 37
  4. 4 SF 29 ARI 34
  5. 5 SF 35 ARI 44
  6. 6 SF 17 ARI 28
  7. 7 SF 6 ARI 20
  8. 8 SF 19 ARI 37
  9. 9 SF 20 ARI 43
  10. 10 SF 10 ARI 41

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

49ers win 19% of them, Cardinals 81%, counting the 2% still level after regulation as half each. The line is what actually happened: Cardinals by 23.

Show as a table
Final margin in the replaysShare of replays
49ers by 17+2.7%
49ers by 9–165.7%
49ers by 1–810.6%
Level after regulation1.6%
Cardinals by 1–822.6%
Cardinals by 9–1620.8%
Cardinals by 17+36.1%

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 +19.5 points to the Cardinals: the final margin was Cardinals by 23, without the luck Cardinals by 3.5. 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. Moody, 51 yds made · 69% expected
  • J. Moody, 47 yds missed · 75% expected
  • C. Ryland, 51 yds made · 69% expected
  • C. Ryland, 49 yds made · 72% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: 49ers 13 for 85 yards, Cardinals 1 for 5 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 6:48 False Start on the 49ers, 5 yards · pre-snap +1% ARI +0.7 pts
Q1 6:38 Ineligible Downfield Pass on the 49ers, 5 yards +2% ARI +0.7 pts
Q1 3:05 Defensive Offside on the 49ers (Leonard Floyd), 5 yards · pre-snap +2% ARI +0.8 pts
Q2 14:06 Defensive Holding on the 49ers (Maliek Collins), 5 yards +2% ARI +0.6 pts
Q2 7:49 Illegal Formation on the 49ers, 5 yards · pre-snap +3% ARI +0.9 pts
Q2 1:55 Encroachment on the 49ers (Jordan Elliott), 3 yards · pre-snap +2% ARI +0.3 pts
Q3 10:26 Illegal Contact on the 49ers (Rock Ya-Sin), 5 yards +2% ARI +0.5 pts
Q3 8:58 Face Mask on the 49ers, 2 yards +2% ARI +0.6 pts
Q3 8:28 Unnecessary Roughness on the 49ers, 1 yard 0% ARI +0.1 pts
Q3 7:53 Offensive Holding on the 49ers (Jacob Cowing), 10 yards +2% ARI +0.8 pts
Q4 14:16 Offensive Holding on the 49ers (Tatum Bethune), 10 yards +1% ARI +1.0 pts
Q4 5:56 Defensive Pass Interference on the 49ers (Rock Ya-Sin), 24 yards +1% ARI +1.5 pts
Q4 5:24 False Start on the 49ers, 5 yards · pre-snap 0% ARI +0.4 pts
Q4 4:48 Defensive Too Many Men on Field on the Cardinals, 5 yards · pre-snap 0% ARI +0.6 pts

49ers penalties, every game · Cardinals penalties, every game · All teams, 2024

When it happened

Cardinals’ chance of winning

As low as 37% 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 Cardinals were ahead in it, below while the 49ers were.
#WhenWhat happenedWin probability forNext drive
1 Q1 2:33 The Cardinals converted 4th & 43rd & 4th downs · 48% expected +13% ARI ARI: Field goal
2 Q1 0:16 The 49ers were stopped on 3rd & 83rd & 4th downs · 34% expectedThe 49ers were intercepted on a well-placed throwInterceptions · 0% expected to stay out of the defense's hands +10% ARI SF: Punt
3 Q2 13:03 The Cardinals converted 3rd & 83rd & 4th downs · 34% expected +8% ARI ARI: Touchdown
4 Q2 8:33 The 49ers fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +7% SF SF: Touchdown
5 Q2 0:21 The 49ers converted 3rd & 63rd & 4th downs · 32% expected +9% SF SF: Touchdown
6 Q3 13:47 The Cardinals were stopped on 3rd & 23rd & 4th downs · 64% expectedT. McBride dropped a catchable passDrops · 4 drops on 236 catchable balls before this +8% SF ARI: Punt
7 Q4 10:16 The 49ers converted 3rd & 83rd & 4th downs · 34% expected +10% SF SF: Turnover
8 Q4 6:40 The 49ers were stopped on 3rd & 103rd & 4th downs · 30% expectedThe 49ers were intercepted on a well-placed throwInterceptions · 0% expected to stay out of the defense's hands +8% ARI SF: Turnover on downs

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.

  • Jonah Williams (ARI T), out (IR) · 1.0 pts
  • Michael Wilson (ARI WR), out · 0.8 pts
  • James Conner (ARI RB), out (IR) · 0.3 pts
  • Jackson Barton (ARI T), out (IR) · 0.3 pts
  • Blake Gillikin (ARI P), out (IR) · 0.2 pts
  • Brock Purdy (SF QB), out, replaced by j.dobbs · 9.0 pts
  • Trent Williams (SF T), out (IR) · 1.2 pts
  • Deommodore Lenoir (SF CB), out · 0.7 pts
  • Christian McCaffrey (SF RB), out (IR) · 0.7 pts
  • De'Vondre Campbell (SF LB), out (IR) · 0.5 pts
  • Jaylon Moore (SF T), out (IR) · 0.4 pts
  • Aaron Banks (SF G), 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

49ers 1% · Cardinals 99%

Final margin
Cardinals by 23
Luck in points
19.5 for the Cardinals
Luck-adjusted margin
Cardinals by 3.5
Replay with same day's form
49ers 19% · Cardinals 81% 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 2024 games · 49ers · Cardinals

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