luckadjusted

Week 4 2024 · September 29, 2024

Rams at Bears, Week 4 2024: who deserved to win?

The Bears beat the Rams 24–18, but the Rams played well enough to win it: they take 7 of 10 replays with the same day's form. Luck ran their way: injuries alone were worth 4.4 points to the Bears.

The Bears won on an off day: their defense played far below its usual level. In a fresh game against the Rams they would win 58% of the time; with this day’s form, 28%. The numbers

Before kickoff the Bears were 59% favorites. The biggest swing (Q2, 1:05 left): J. Karty missed 43-yard field goal, worth 15 points of win probability to the Bears.

Final

Los Angeles Rams 18
Chicago Bears 24

September 29, 2024 · Soldier Field · Closing line: Bears −3

Luck index +72 Bears very lucky · −72 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. Rams win 7, Bears win 3.

  1. 1 LA 41 CHI 17
  2. 2 LA 23 CHI 6
  3. 3 LA 27 CHI 14
  4. 4 LA 19 CHI 9
  5. 5 LA 20 CHI 13
  6. 6 LA 16 CHI 12
  7. 7 LA 24 CHI 22
  8. 8 LA 25 CHI 27
  9. 9 LA 13 CHI 19
  10. 10 LA 7 CHI 21

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.

The Bears won on an off day

Their defense played far below its usual level. In a fresh game against the Rams they would win 58% of the time; with this day’s form, 28%.

30 points apart for the Bears: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Rams offenseEPA per play gained +0.19 +0.10 better by 0.09
Rams defenseEPA per play allowed +0.09 +0.10 better by 0.01
Bears offenseEPA per play gained +0.09 +0.02 better by 0.07
Bears defenseEPA per play allowed +0.19 +0.06 worse by 0.13

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

Rams win 72% of them, Bears 28%, counting the 5% still level after regulation as half each. The line is what actually happened: Bears by 6.

Show as a table
Final margin in the replaysShare of replays
Rams by 17+23.1%
Rams by 9–1621.1%
Rams by 1–826.0%
Level after regulation4.5%
Bears by 1–815.5%
Bears by 9–166.9%
Bears by 17+2.8%

Where the luck was

Take the luck out

The final margin was Bears by 6. Remove the luck, one kind at a time, and it becomes Rams by 2.9.

Each row takes one kind of luck out of the margin. Color shows which team it helped. Luck shares are the fitted ones (how much of each component 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. Karty, 46 yds made · 74% expected
  • J. Karty, 37 yds made · 89% expected
  • J. Karty, 43 yds missed · 79% expected
  • C. Santos, 40 yds made · 85% expected
  • J. Karty, 25 yds made · 98% expected
  • J. Karty, 52 yds made · 63% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Bears’ chance of winning

As low as 27% 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 Bears were ahead in it, below while the Rams were.
#WhenWhat happenedWin probability forNext drive
1 Q2 10:10 Defensive Holding on the Rams (Tre'Davious White), 5 yards, wiping out the playJudgment calls · 26 flags in 3761 snaps before, position avg 1 per 215 +7% CHI CHI: Punt
2 Q2 6:51 The Rams fumbled and the Bears recoveredFumble bounces · loose balls are close to 50/50 +7% CHI LA: Missed field goal
3 Q2 5:52 Defensive Pass Interference on the Rams (Tre'Davious White), 14 yardsJudgment calls · 26 flags in 3761 snaps before, position avg 1 per 215 +10% CHI CHI: Touchdown
4 Q2 1:05 J. Karty missed 43-yard field goalKicks · 79% expected for him +15% CHI LA: End of half
5 Q3 12:24 Defensive Pass Interference on the Bears (Tyrique Stevenson), 14 yardsJudgment calls · 5 flags in 1152 snaps before, position avg 1 per 215 +8% LA LA: Field goal
6 Q3 2:43 The Bears converted 3rd & 53rd & 4th downs · 35% expected +7% CHI CHI: Touchdown
7 Q4 14:55 The Rams’ two-point try failed3rd & 4th downs · 47% expected +7% CHI LA: Field goal
8 Q4 7:25 The Bears were stopped on 3rd & 73rd & 4th downs · 36% expectedFalse Start on the Bears (Cole Kmet), 5 yardsPre-snap flags · 15 flags in 3937 snaps before, position avg 1 per 280 +10% LA CHI: Punt

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.

  • Patrick Scales (CHI LS), out (IR) · 0.1 pts
  • Puka Nacua (LA WR), out (IR) · 1.6 pts
  • Cooper Kupp (LA WR), out · 1.3 pts
  • Tyler Higbee (LA TE), out (IR) · 0.7 pts
  • John Johnson (LA SS), out (IR) · 0.5 pts
  • Steve Avila (LA 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

Rams 43% · Bears 57%

Final margin
Bears by 6
Luck in points
8.9 for the Bears
Luck-adjusted margin
Rams by 2.9
Replay with same day's form
Rams 72% · Bears 28% 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 4 2024 games · Rams · Bears

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