luckadjusted

Week 17 2025 · December 28, 2025

Bears at 49ers, Week 17 2025: who deserved to win?

The 49ers beat the Bears 42–38, and it was no fluke: replayed with the way both teams actually played, the 49ers win 9 of 10.

Before kickoff the 49ers were 60% favorites. The biggest swing (Q1, 14:54 left): Return touchdown by the Bears, worth 26 points of win probability to the Bears.

Final

Chicago Bears 38
San Francisco 49ers 42

December 28, 2025 · Levi's Stadium · Closing line: 49ers −3.5

Luck index +14 49ers about even · −14 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 1, 49ers win 9.

  1. 1 CHI 34 SF 28
  2. 2 CHI 35 SF 37
  3. 3 CHI 38 SF 43
  4. 4 CHI 24 SF 31
  5. 5 CHI 14 SF 24
  6. 6 CHI 37 SF 49
  7. 7 CHI 19 SF 34
  8. 8 CHI 34 SF 52
  9. 9 CHI 33 SF 55
  10. 10 CHI 13 SF 45

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 14% of them, 49ers 86%, counting the 1% still level after regulation as half each. The line is what actually happened: 49ers by 4.

Show as a table
Final margin in the replaysShare of replays
Bears by 17+1.0%
Bears by 9–163.3%
Bears by 1–89.1%
Level after regulation1.2%
49ers by 1–825.7%
49ers by 9–1623.7%
49ers by 17+36.1%

Where the luck was

Take the luck out

The final margin was 49ers by 4. 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).

When it happened

49ers’ chance of winning

As low as 31% 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 49ers were ahead in it, below while the Bears were.
#WhenWhat happenedWin probability forNext drive
1 Q1 14:54 The 49ers threw an interception-worthy pass, and it was pickedInterceptions · 55% expected to stay out of the defense's handsReturn touchdown by the BearsSpecial teams +26% CHI SF: Touchdown
2 Q2 4:21 Illegal Use of Hands on the Bears (C.J. Gardner-Johnson), 4 yards, wiping out the playJudgment calls · 26 flags in 5636 snaps before, position avg 1 per 244 +19% SF SF: Touchdown
3 Q3 3:02 The Bears converted 3rd & 83rd & 4th downs · 33% expected +10% CHI CHI: Touchdown
4 Q3 0:16 The Bears converted 4th & 53rd & 4th downs · 42% expected +10% CHI CHI: Touchdown
5 Q4 1:17 C. Loveland dropped a catchable passDrops · 0 drops on 46 catchable balls before this +22% SF CHI: End of game
6 Q4 1:09 The Bears converted 3rd & 103rd & 4th downs · 29% expected +13% CHI CHI: End of game
7 Q4 0:36 The Bears were stopped on 3rd & 53rd & 4th downs · 43% expectedL. Burden dropped a catchable passDrops · 4 drops on 49 catchable balls before this +25% SF CHI: End of game
8 Q4 0:33 The Bears converted 4th & 53rd & 4th downs · 42% expected +21% CHI CHI: 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.

  • George Kittle (SF TE), out · 1.1 pts
  • Renardo Green (SF CB), out · 0.6 pts
  • Mykel Williams (SF DL), out (IR) · 0.3 pts
  • Curtis Robinson (SF LB), out · 0.2 pts
  • Rome Odunze (CHI WR), out · 0.6 pts
  • Olamide Zaccheaus (CHI WR), out · 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

Bears 46% · 49ers 54%

Final margin
49ers by 4
Luck in points
1.8 for the 49ers
Luck-adjusted margin
49ers by 2.2
Replay with same day's form
Bears 14% · 49ers 86% 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 17 2025 games · Bears · 49ers

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