luckadjusted

Week 15 2024 · December 12, 2024

Rams at 49ers, Week 15 2024: who deserved to win?

The Rams beat the 49ers 12–6, but it was a coin flip: replayed with the way both teams played, the Rams win 6 of 10. Luck ran their way: drops alone were worth 3.4 points to the Rams.

Before kickoff the 49ers were 59% favorites. The biggest swing (Q4, 5:20 left): the 49ers threw an interception-worthy pass, and it was picked, worth 10 points of win probability to the Rams.

Final

Los Angeles Rams 12
San Francisco 49ers 6

December 12, 2024 · Levi's Stadium · Closing line: 49ers −3

Luck index +40 Rams lucky · −40 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. Rams win 6, 49ers win 4.

  1. 1 LA 27 SF 3
  2. 2 LA 23 SF 7
  3. 3 LA 27 SF 16
  4. 4 LA 31 SF 23
  5. 5 LA 31 SF 27
  6. 6 LA 23 SF 20
  7. 7 LA 10 SF 13
  8. 8 LA 10 SF 16
  9. 9 LA 8 SF 20
  10. 10 LA 7 SF 27

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

Rams win 60% of them, 49ers 40%, counting the 3% still level after regulation as half each. The line is what actually happened: Rams by 6.

Show as a table
Final margin in the replaysShare of replays
Rams by 17+14.1%
Rams by 9–1617.2%
Rams by 1–827.1%
Level after regulation2.9%
49ers by 1–819.8%
49ers by 9–1613.0%
49ers by 17+5.9%

Where the luck was

Take the luck out

The final margin was Rams by 6. Remove the luck, one kind at a time, and it becomes Rams by 3.1.

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. Moody, 53 yds made · 64% expected
  • J. Karty, 48 yds made · 75% expected
  • J. Moody, 47 yds made · 75% expected
  • J. Karty, 23 yds made · 98% expected
  • J. Karty, 27 yds made · 97% expected
  • J. Karty, 29 yds made · 96% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

49ers’ chance of winning

As low as 0% and as high as 69%. 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 49ers were ahead in it, below while the Rams were.
#WhenWhat happenedWin probability forNext drive
1 Q1 2:46 The 49ers were stopped on 3rd & 63rd & 4th downs · 36% expected +7% LA SF: Punt
2 Q2 13:52 The 49ers were stopped on 3rd & 93rd & 4th downs · 29% expectedJ. Jennings dropped a catchable passDrops · 3 drops on 136 catchable balls before this +8% LA SF: Punt
3 Q2 7:02 The 49ers converted 3rd & 83rd & 4th downs · 31% expected +7% SF SF: Punt
4 Q3 8:31 The 49ers were stopped on 3rd & 103rd & 4th downs · 27% expectedD. Samuel dropped a catchable passDrops · 10 drops on 211 catchable balls before this +8% LA SF: Field goal
5 Q3 5:06 The Rams converted 4th & 13rd & 4th downs · 73% expected +8% LA LA: Field goal
6 Q4 13:49 The Rams were stopped on 3rd & 43rd & 4th downs · 37% expected +7% SF LA: Field goal
7 Q4 5:20 The 49ers threw an interception-worthy pass, and it was pickedInterceptions · 51% expected to stay out of the defense's hands +10% LA SF: End of game
8 Q4 0:18 Horse Collar Tackle on the Rams, 15 yardsJudgment calls +10% SF SF: End of game

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.

  • Trent Williams (SF T), out · 1.2 pts
  • Brandon Aiyuk (SF WR), out (IR) · 1.1 pts
  • Christian McCaffrey (SF RB), out (IR) · 0.7 pts
  • Malik Mustapha (SF FS), out · 0.4 pts
  • Mitch Wishnowsky (SF P), out (IR) · 0.2 pts
  • Cobie Durant (LA CB), out · 0.6 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 86% · 49ers 14%

Final margin
Rams by 6
Luck in points
2.9 for the Rams
Luck-adjusted margin
Rams by 3.1
Replay with same day's form
Rams 60% · 49ers 40% 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 15 2024 games · Rams · 49ers

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