luckadjusted

Week 13 2024 · December 1, 2024

49ers at Bills, Week 13 2024: who deserved to win?

The Bills beat the 49ers 35–10, and it was no fluke: replayed with the way both teams actually played, the Bills win 9 of 10. The 49ers had the bounces: judgment calls alone were worth 4.7 points to the 49ers.

Before kickoff the Bills were 68% favorites. The biggest swing (Q2, 11:33 left): Illegal Contact on the Bills (Rasul Douglas), 5 yards, wiping out the play, worth 19 points of win probability to the 49ers.

Final

San Francisco 49ers 10
Buffalo Bills 35

December 1, 2024 · New Era Field · Closing line: Bills −6.5

Luck index +5 Bills about even · −5 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. 49ers win 1, Bills win 9.

  1. 1 SF 45 BUF 38
  2. 2 SF 31 BUF 34
  3. 3 SF 21 BUF 27
  4. 4 SF 19 BUF 28
  5. 5 SF 14 BUF 26
  6. 6 SF 7 BUF 21
  7. 7 SF 13 BUF 31
  8. 8 SF 21 BUF 41
  9. 9 SF 21 BUF 46
  10. 10 SF 9 BUF 41

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 5% of them, Bills 95%. The line is what actually happened: Bills by 25.

Show as a table
Final margin in the replaysShare of replays
49ers by 17+0.1%
49ers by 9–161.0%
49ers by 1–83.8%
Level after regulation0.4%
Bills by 1–814.1%
Bills by 9–1619.8%
Bills by 17+60.8%

Where the luck was

Take the luck out

The final margin was Bills by 25. Remove the luck, one kind at a time, and it becomes Bills by 13.1.

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, 33 yds made · 92% expected
  • J. Moody, 45 yds missed · 73% expected
  • J. Moody, 55 yds missed · 53% expected
  • T. Bass, 49 yds missed · 66% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Bills’ chance of winning

As low as 38% 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 Bills were ahead in it, below while the 49ers were.
#WhenWhat happenedWin probability forNext drive
1 Q1 11:05 The 49ers converted 3rd & 13rd & 4th downs · 73% expected +5% SF SF: Field goal
2 Q1 7:47 The 49ers were stopped on 3rd & 73rd & 4th downs · 33% expected +4% BUF SF: Field goal
3 Q1 6:50 Illegal Contact on the 49ers, 5 yardsJudgment calls +7% BUF BUF: Touchdown
4 Q1 2:57 The Bills converted 3rd & 63rd & 4th downs · 42% expected +5% BUF BUF: Touchdown
5 Q1 0:50 The Bills converted 3rd & 13rd & 4th downs · 78% expected +4% BUF BUF: Touchdown
6 Q2 11:33 Illegal Contact on the Bills (Rasul Douglas), 5 yards, wiping out the playJudgment calls · 34 flags in 5452 snaps before, position avg 1 per 215 +19% SF SF: Missed field goal
7 Q2 8:52 J. Moody missed 45-yard field goalKicks · 73% expected for him, 10 of 16 from 45+ before +9% BUF SF: Punt
8 Q2 4:26 The 49ers were stopped on 3rd & 93rd & 4th downs · 29% expected +3% BUF SF: 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.

  • Dalton Kincaid (BUF TE), out · 0.8 pts
  • Keon Coleman (BUF WR), out · 0.6 pts
  • Dawuane Smoot (BUF DE), out (IR) · 0.2 pts
  • Brandon Aiyuk (SF WR), out (IR) · 1.4 pts
  • Trent Williams (SF T), out · 1.2 pts
  • Nick Bosa (SF DE), out · 1.1 pts
  • Deommodore Lenoir (SF CB), out · 0.7 pts
  • Aaron Banks (SF G), out · 0.4 pts
  • Jordan Elliott (SF DT), out · 0.2 pts
  • Mitch Wishnowsky (SF P), 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

49ers 0% · Bills 100%

Final margin
Bills by 25
Luck in points
11.9 for the Bills
Luck-adjusted margin
Bills by 13.1
Replay with same day's form
49ers 5% · Bills 95% 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 13 2024 games · 49ers · Bills

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