luckadjusted

Week 2 2023 · September 17, 2023

49ers at Rams, Week 2 2023: who deserved to win?

The 49ers beat the Rams 30–23 and were the better team on the day: replayed with the same form, they win 7 of 10.

Before kickoff the 49ers were 71% favorites. The biggest swing (Q4, 4:58 left): the Rams were stopped on 3rd & 5, worth 19 points of win probability to the 49ers.

Final

San Francisco 49ers 30
Los Angeles Rams 23

September 17, 2023 · SoFi Stadium · Closing line: 49ers −7.5

Luck index +34 49ers lucky · −34 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. 49ers win 7, Rams win 3.

  1. 1 SF 41 LA 13
  2. 2 SF 44 LA 24
  3. 3 SF 40 LA 24
  4. 4 SF 24 LA 13
  5. 5 SF 19 LA 10
  6. 6 SF 21 LA 15
  7. 7 SF 24 LA 22
  8. 8 SF 21 LA 24
  9. 9 SF 30 LA 37
  10. 10 SF 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

49ers win 66% of them, Rams 34%, counting the 3% still level after regulation as half each. The line is what actually happened: 49ers by 7.

Show as a table
Final margin in the replaysShare of replays
49ers by 17+18.7%
49ers by 9–1619.9%
49ers by 1–825.6%
Level after regulation2.7%
Rams by 1–819.3%
Rams by 9–169.3%
Rams by 17+4.5%

Where the luck was

Take the luck out

The final margin was 49ers by 7. Remove the luck, one kind at a time, and it becomes 49ers by 2.2.

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.

  • B. Maher, 43 yds made · 84% expected
  • J. Moody, 27 yds made · 98% expected
  • J. Moody, 57 yds made · 64% expected
  • B. Maher, 48 yds made · 75% expected
  • J. Moody, 26 yds made · 98% expected
  • B. Maher, 38 yds made · 90% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Rams’ chance of winning

As low as 0% and as high as 78%. 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 49ers were.
#WhenWhat happenedWin probability forNext drive
1 Q1 9:33 The 49ers converted 3rd & 73rd & 4th downs · 37% expected +8% SF SF: Touchdown
2 Q1 3:55 Offensive Holding on the Rams (Tyler Higbee), 10 yards, wiping out the playJudgment calls · 9 flags in 3774 snaps before, position avg 1 per 286 +7% SF SF: Field goal
3 Q2 0:17 Defensive Pass Interference on the Rams (Derion Kendrick), 19 yardsJudgment calls · 4 flags in 573 snaps before, position avg 1 per 216 +8% SF SF: Touchdown
4 Q3 4:17 The Rams were intercepted on a well-placed throwInterceptions · 0% expected to stay out of the defense's hands +8% SF LA: Punt
5 Q3 1:26 J. Moody made 57-yard field goalKicks · 64% expected for him, 0 of 0 from 45+ before +13% SF SF: Touchdown
6 Q4 10:18 The Rams converted 4th & 23rd & 4th downs · 61% expected +7% LA LA: Field goal
7 Q4 4:58 The Rams were stopped on 3rd & 53rd & 4th downs · 42% expectedThe Rams were intercepted on a well-placed throwInterceptions · 0% expected to stay out of the defense's hands +19% SF LA: Turnover on downs
8 Q4 0:49 The Rams got away with an interception-worthy throwInterceptions · 49% expected to stay out of the defense's hands +7% 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.

  • Cam Akers (LA RB), out · 0.1 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 63% · Rams 37%

Final margin
49ers by 7
Luck in points
4.8 for the 49ers
Luck-adjusted margin
49ers by 2.2
Replay with same day's form
49ers 66% · Rams 34% 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 2 2023 games · 49ers · Rams

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