luckadjusted

Week 14 2024 · December 8, 2024

Bears at 49ers, Week 14 2024: who deserved to win?

The 49ers beat the Bears 38–13, and it was no fluke: replayed with the way both teams actually played, the 49ers win 10 of 10. The Bears had the bounces: injuries alone were worth 11 points of win probability to the Bears.

Before kickoff the 49ers were 59% favorites.

Final

Chicago Bears 13
San Francisco 49ers 38

December 8, 2024 · Levi's Stadium · Closing line: 49ers −3

Luck index +1 49ers about even · −1 Bears

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. Bears win 0, 49ers win 10.

  1. 1 CHI 17 SF 20
  2. 2 CHI 10 SF 20
  3. 3 CHI 7 SF 21
  4. 4 CHI 7 SF 23
  5. 5 CHI 13 SF 32
  6. 6 CHI 13 SF 34
  7. 7 CHI 12 SF 36
  8. 8 CHI 3 SF 31
  9. 9 CHI 12 SF 44
  10. 10 CHI 3 SF 44

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

Bears win 1% of them, 49ers 99%. The line is what actually happened: 49ers by 25.

Show as a table
Final margin in the replaysShare of replays
Bears by 17+0.0%
Bears by 9–160.1%
Bears by 1–80.8%
Level after regulation0.4%
49ers by 1–84.0%
49ers by 9–1613.2%
49ers by 17+81.6%

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 +1.8 points to the 49ers: the final margin was 49ers by 25, without the luck 49ers by 23.2. Luck shares are the fitted ones (how much of each kind is luck).

Penalties: Bears 2 for 30 yards, 49ers 7 for 31 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
Q2 3:25 Offensive Holding on the 49ers (Ricky Pearsall), 10 yards 0% CHI +1.0 pts
Q2 1:50 Kickoff Short of Landing Zone on the 49ers (Jake Moody), 0 yards · pre-snap 0% CHI 0.0 pts
Q2 0:14 Offensive Holding on the 49ers (Isaac Yiadom), 6 yards 0% CHI +0.6 pts
Q3 5:56 False Start on the 49ers (George Kittle), 5 yards · pre-snap 0% CHI +0.7 pts
Q4 14:57 Kickoff Short of Landing Zone on the 49ers (Jake Moody), 0 yards · pre-snap 0% CHI 0.0 pts
Q4 11:06 Roughing the Passer on the Bears (Darrell Taylor), 15 yards 0% SF +1.5 pts
Q4 11:06 False Start on the 49ers, 5 yards · pre-snap 0% CHI +0.5 pts
Q4 3:42 Unnecessary Roughness on the Bears (Tarvarius Moore), 15 yards 0% SF +1.1 pts
Q4 2:04 Delay of Game on the 49ers, 5 yards · pre-snap 0% CHI +0.4 pts

Bears penalties, every game · 49ers penalties, every game · All teams, 2024

When it happened

49ers’ chance of winning

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 Bears were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:54 The 49ers converted 3rd & 33rd & 4th downs · 56% expected +6% SF SF: Touchdown
2 Q1 10:59 The Bears were stopped on 3rd & 73rd & 4th downs · 34% expected +2% SF CHI: Punt
3 Q1 6:23 The 49ers were stopped on 3rd & 53rd & 4th downs · 45% expected +3% CHI SF: Punt
4 Q1 4:47 D. Moore dropped a catchable passDrops · 8 drops on 246 catchable balls before this +3% SF CHI: Punt
5 Q1 4:43 The Bears were stopped on 3rd & 103rd & 4th downs · 27% expected +4% SF CHI: Punt
6 Q2 12:55 The 49ers converted 3rd & 83rd & 4th downs · 35% expected +3% SF SF: Touchdown
7 Q2 1:53 J. Moody made 23-yard field goalKicks · 98% expected for him +4% SF SF: End of half
8 Q3 6:01 The Bears converted 3rd & 43rd & 4th downs · 37% expected +2% CHI CHI: Touchdown

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.

  • Brandon Aiyuk (SF WR), out (IR) · 1.5 pts
  • Trent Williams (SF T), out · 1.2 pts
  • Nick Bosa (SF DE), out · 1.2 pts
  • Christian McCaffrey (SF RB), out (IR) · 0.7 pts
  • Aaron Banks (SF G), out · 0.4 pts
  • Mitch Wishnowsky (SF P), out (IR) · 0.2 pts
  • Larry Borom (CHI T), out · 0.4 pts
  • Elijah Hicks (CHI FS), out · 0.3 pts
  • Ryan Bates (CHI C), out · 0.2 pts
  • Andrew Billings (CHI DT), 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

Bears 0% · 49ers 100%

Final margin
49ers by 25
Luck in points
1.8 for the 49ers
Luck-adjusted margin
49ers by 23.2
Replay with same day's form
Bears 1% · 49ers 99% 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 14 2024 games · Bears · 49ers

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