luckadjusted

Week 17 2020 · January 3, 2021

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

Cardinals at Rams, Week 17 2020: who deserved to win?

The Rams beat the Cardinals 18–7, but it was a coin flip: replayed with the way both teams played, the Rams win 5 of 10. Luck ran their way: judgment calls alone were worth 26 points of win probability to the Rams.

Before kickoff it was a pick’em. The biggest swing (Q2, 0:37 left): Return touchdown by the Rams, worth 38 points of win probability to the Rams.

Final

Arizona Cardinals 7
Los Angeles Rams 18

January 3, 2021 · SoFi Stadium · Closing line: Rams −1

Luck index +54 Rams lucky · −54 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. Cardinals win 5, Rams win 5.

  1. 1 ARI 30 LA 12
  2. 2 ARI 31 LA 17
  3. 3 ARI 26 LA 17
  4. 4 ARI 24 LA 20
  5. 5 ARI 23 LA 20
  6. 6 ARI 17 LA 19
  7. 7 ARI 24 LA 29
  8. 8 ARI 17 LA 26
  9. 9 ARI 10 LA 23
  10. 10 ARI 9 LA 30

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 54% of them, Rams 46%, counting the 6% still level after regulation as half each. The line is what actually happened: Rams by 11.

Show as a table
Final margin in the replaysShare of replays
Cardinals by 17+11.1%
Cardinals by 9–1615.9%
Cardinals by 1–822.1%
Level after regulation5.6%
Rams by 1–821.2%
Rams by 9–1614.6%
Rams by 17+9.5%

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.

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 +5.8 points to the Rams: the final margin was Rams by 11, without the luck Rams by 5.2. 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.

  • M. Gay, 28 yds made · 97% expected
  • M. Gay, 34 yds made · 94% expected
  • M. Gay, 27 yds made · 97% expected
  • M. Nugent, 37 yds blocked · 91% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Cardinals 5 for 28 yards, Rams 5 for 38 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 2:55 False Start on the Rams, 5 yards · pre-snap +2% ARI +0.8 pts
Q1 1:10 Defensive Pass Interference on the Cardinals (Dre Kirkpatrick), 1 yard +4% LA +1.1 pts
Q1 0:30 False Start on the Rams (Van Jefferson), 5 yards · pre-snap +3% ARI +1.1 pts
Q1 0:05 False Start on the Rams, 5 yards · pre-snap +2% ARI +0.8 pts
Q2 5:31 Offensive Holding on the Cardinals, 2 yards +7% LA +1.6 pts
Q2 0:47 Defensive Pass Interference on the Rams (Jalen Ramsey), 18 yards +6% ARI +1.3 pts
Q3 12:03 Defensive Holding on the Cardinals (Patrick Peterson), 5 yards +2% LA +0.6 pts
Q3 8:33 False Start on the Rams, 5 yards · pre-snap +1% ARI +0.7 pts
Q3 5:21 Offensive Pass Interference on the Cardinals (DeAndre Hopkins), 15 yards, wiping out the play +18% LA +6.7 pts
Q4 5:52 Illegal Shift on the Cardinals, 5 yards · pre-snap +2% LA +0.6 pts

Cardinals penalties, every game · Rams penalties, every game · All teams, 2020

When it happened

Rams’ chance of winning

As low as 33% 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 Rams were ahead in it, below while the Cardinals were.
#WhenWhat happenedWin probability forNext drive
1 Q1 6:51 The Rams converted 3rd & 103rd & 4th downs · 26% expected +6% LA LA: Field goal
2 Q2 10:25 The Rams converted 3rd & 53rd & 4th downs · 39% expected +10% LA LA: Turnover
3 Q2 6:17 The Rams fumbled and the Cardinals recoveredFumble bounces · loose balls are close to 50/50 +8% ARI LA: Punt
4 Q2 5:31 Offensive Holding on the Cardinals, 2 yardsJudgment calls +7% LA LA: Punt
5 Q2 0:47 Defensive Pass Interference on the Rams (Jalen Ramsey), 18 yardsJudgment calls · 8 flags in 1699 snaps before, position avg 1 per 207 +6% ARI ARI: Opp touchdown
6 Q2 0:37 Return touchdown by the RamsSpecial teams +38% LA LA: Opp touchdown
7 Q3 9:13 The Rams converted 3rd & 113rd & 4th downs · 25% expected +5% LA LA: Field goal
8 Q3 5:21 Offensive Pass Interference on the Cardinals (DeAndre Hopkins), 15 yards, wiping out the playJudgment calls · 4 flags in 2111 snaps before, position avg 1 per 385 +18% LA LA: 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.

  • Jared Goff (LA QB), out, replaced by j.wolford · 5.6 pts
  • Cooper Kupp (LA WR), out (IR) · 1.0 pts
  • Andrew Whitworth (LA OL), out (IR) · 0.5 pts
  • Michael Brockers (LA DL), out (IR) · 0.5 pts
  • Kai Forbath (LA K), out (IR) · 0.3 pts
  • Taylor Rapp (LA S), out (IR) · 0.3 pts
  • Micah Kiser (LA ILB), out · 0.2 pts
  • Christian Kirk (ARI WR), out (IR) · 0.9 pts
  • Larry Fitzgerald (ARI WR), out · 0.9 pts
  • Zane Gonzalez (ARI K), out (IR) · 0.3 pts
  • Chris Banjo (ARI S), 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

Cardinals 52% · Rams 48%

Final margin
Rams by 11
Luck in points
5.8 for the Rams
Luck-adjusted margin
Rams by 5.2
Replay with same day's form
Cardinals 54% · Rams 46% 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 17 2020 games · Cardinals · Rams

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