luckadjusted

Week 4 2021 · October 3, 2021

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

Cardinals at Rams, Week 4 2021: who deserved to win?

The Cardinals beat the Rams 37–20 and were the better team on the day: replayed with the same form, they win 7 of 10. The Rams had the bounces: judgment calls alone were worth 11 points of win probability to the Rams.

Before kickoff the Rams were 60% favorites. The biggest swing (Q1, 5:58 left): the Cardinals converted 3rd & 6, worth 14 points of win probability to the Cardinals.

Final

Arizona Cardinals 37
Los Angeles Rams 20

October 3, 2021 · SoFi Stadium · Closing line: Rams −3.5

Luck index +29 Cardinals lucky · −29 Rams

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 7, Rams win 3.

  1. 1 ARI 50 LA 24
  2. 2 ARI 42 LA 23
  3. 3 ARI 24 LA 10
  4. 4 ARI 36 LA 26
  5. 5 ARI 28 LA 21
  6. 6 ARI 21 LA 17
  7. 7 ARI 31 LA 30
  8. 8 ARI 19 LA 21
  9. 9 ARI 19 LA 26
  10. 10 ARI 17 LA 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 71% of them, Rams 29%, counting the 4% still level after regulation as half each. The line is what actually happened: Cardinals by 17.

Show as a table
Final margin in the replaysShare of replays
Cardinals by 17+22.4%
Cardinals by 9–1621.1%
Cardinals by 1–827.3%
Level after regulation3.7%
Rams by 1–815.3%
Rams by 9–166.9%
Rams by 17+3.4%

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 +4.0 points to the Cardinals: the final margin was Cardinals by 17, without the luck Cardinals by 13. 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.

  • M. Gay, 42 yds made · 86% expected
  • M. Gay, 22 yds made · 99% expected
  • M. Prater, 23 yds made · 98% expected
  • M. Prater, 55 yds made · 64% expected
  • M. Gay, 46 yds missed · 82% expected
  • M. Prater, 23 yds made · 98% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Cardinals 7 for 63 yards, Rams 5 for 36 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 13:41 False Start on the Rams, 5 yards · pre-snap +1% ARI +0.6 pts
Q1 8:11 Offensive Holding on the Cardinals, 10 yards, wiping out the play +6% LA +2.1 pts
Q2 10:08 False Start on the Cardinals, 5 yards · pre-snap +1% LA +0.5 pts
Q2 8:13 Defensive Holding on the Cardinals, 5 yards +2% LA +0.3 pts
Q2 6:41 Offensive Holding on the Rams, 10 yards +3% ARI +0.9 pts
Q2 4:57 Delay of Game on the Rams, 5 yards · pre-snap +3% ARI +0.8 pts
Q2 3:22 False Start on the Cardinals, 5 yards · pre-snap +2% LA +0.5 pts
Q2 1:16 Offensive Holding on the Cardinals, 10 yards +2% LA +1.2 pts
Q2 0:24 Roughing the Passer on the Rams (Leonard Floyd), 6 yards, wiping out the play +6% ARI +2.4 pts
Q3 9:47 Roughing the Passer on the Cardinals (Isaiah Simmons), 15 yards, wiping out the play +12% LA +3.5 pts
Q3 0:37 Illegal Use of Hands on the Rams, 10 yards 0% ARI +0.8 pts
Q3 0:01 Defensive Pass Interference on the Cardinals, 13 yards +1% LA +0.7 pts

Cardinals penalties, every game · Rams penalties, every game · All teams, 2021

When it happened

Rams’ chance of winning

As low as 0% and as high as 68%. 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 Rams were ahead in it, below while the Cardinals were.
#WhenWhat happenedWin probability forNext drive
1 Q1 12:34 The Rams converted 3rd & 73rd & 4th downs · 35% expected +11% LA LA: Field goal
2 Q1 5:58 The Cardinals converted 3rd & 63rd & 4th downs · 37% expected +14% ARI ARI: Touchdown
3 Q2 10:44 The Rams fumbled and the Cardinals recoveredFumble bounces · loose balls are close to 50/50 +6% ARI LA: Punt
4 Q2 9:40 The Cardinals converted 3rd & 163rd & 4th downs · 21% expected +7% ARI ARI: Touchdown
5 Q2 5:47 The Rams converted 3rd & 163rd & 4th downs · 21% expected +10% LA LA: Field goal
6 Q2 3:25 M. Gay made 22-yard field goalKicks · 99% expected for him +7% ARI LA: End of half
7 Q2 0:07 M. Prater made 23-yard field goalKicks · 98% expected for him +9% LA ARI: Field goal
8 Q3 9:47 Roughing the Passer on the Cardinals (Isaiah Simmons), 15 yards, wiping out the playJudgment calls · 5 flags in 675 snaps before, position avg 1 per 409 +12% LA LA: Missed field goal

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.

  • Cam Akers (LA RB), out (IR) · 0.1 pts
  • Justin Hollins (LA LB), out (IR) · 0.1 pts
  • Kelvin Beachum (ARI OL), out · 0.5 pts
  • Kelvin Beachum (ARI T), out · 0.4 pts
  • Justin Murray (ARI OL), out · 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 97% · Rams 3%

Final margin
Cardinals by 17
Luck in points
4.0 for the Cardinals
Luck-adjusted margin
Cardinals by 13.0
Replay with same day's form
Cardinals 71% · Rams 29% 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 4 2021 games · Cardinals · Rams

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