luckadjusted
NFL Week 9 · 2026

Week 4 2023 · October 1, 2023

Broncos at Bears, Week 4 2023: who deserved to win?

The Broncos beat the Bears 31–28, but the replays call it close to a coin flip: with the way both teams played, the Broncos win 5 of 10. Luck ran their way: fumble bounces alone were worth 17 points of win probability to the Broncos.

Before kickoff the Broncos were 59% favorites. The game turned on a luck play (Q4, 7:05 left): Return touchdown by the Broncos, worth 50 points of win probability to the Broncos.

Final

Denver Broncos 31
Chicago Bears 28

October 1, 2023 · Soldier Field · Closing line: Broncos −3

Luck index +52 Broncos lucky · −52 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. Broncos win 5, Bears win 5.

  1. 1 DEN 41 CHI 20
  2. 2 DEN 22 CHI 10
  3. 3 DEN 34 CHI 27
  4. 4 DEN 20 CHI 16
  5. 5 DEN 8 CHI 6
  6. 6 DEN 14 CHI 16
  7. 7 DEN 24 CHI 28
  8. 8 DEN 20 CHI 28
  9. 9 DEN 14 CHI 27
  10. 10 DEN 14 CHI 36

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

Broncos win 48% of them, Bears 52%, counting the 6% still level after regulation as half each. The line is what actually happened: Broncos by 3.

Show as a table
Final margin in the replaysShare of replays
Broncos by 17+9.0%
Broncos by 9–1614.8%
Broncos by 1–822.5%
Level after regulation6.0%
Bears by 1–823.5%
Bears by 9–1615.1%
Bears by 17+9.2%

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 +5.9 points to the Broncos: the final margin was Broncos by 3, without the luck Bears by 2.9. Luck shares are the fitted ones (how much of each kind is luck).

Penalties: Broncos 7 for 39 yards, Bears 10 for 91 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 half toward luck; pre-snap fouls, which repeat, don’t count. How calls are valued

WhenFlagWin probability for
Q1 8:40 Lowering the Head to Make Forcible Contact on the Bears (Jack Sanborn), 15 yards +6% DEN +1.8 pts
Q2 13:00 False Start on the Bears (Tyler Scott), 5 yards · pre-snap +1% DEN +0.6 pts
Q2 10:20 False Start on the Broncos, 5 yards · pre-snap +1% CHI +0.3 pts
Q2 6:21 Defensive Pass Interference on the Broncos (Kareem Jackson), 10 yards +3% CHI +1.3 pts
Q2 3:40 False Start on the Broncos, 5 yards · pre-snap +1% CHI +0.3 pts
Q2 2:29 False Start on the Bears, 5 yards · pre-snap +1% DEN +0.2 pts
Q2 0:06 False Start on the Bears, 5 yards · pre-snap +1% DEN 0.0 pts
Q3 14:16 False Start on the Broncos, 5 yards · pre-snap 0% CHI +1.1 pts
Q3 9:24 Illegal Block Above the Waist on the Bears, 10 yards +1% DEN +0.9 pts
Q3 4:11 Roughing the Passer on the Bears (Jaquan Brisker), 15 yards 0% DEN +1.8 pts
Q3 2:25 False Start on the Broncos, 5 yards · pre-snap 0% CHI +0.8 pts
Q3 0:14 Defensive Holding on the Broncos (Patrick Surtain II), 5 yards 0% CHI +0.3 pts
Q4 12:38 False Start on the Broncos, 4 yards · pre-snap +2% CHI +1.0 pts
Q4 6:55 Offensive Holding on the Bears (Marcedes Lewis), 10 yards +8% DEN +0.9 pts
Q4 5:49 False Start on the Bears, 5 yards · pre-snap +3% DEN +0.6 pts
Q4 4:07 Offensive Holding on the Bears, 10 yards +3% DEN +0.9 pts
Q4 0:50 Intentional Grounding on the Bears (Justin Fields), 11 yards +13% DEN +1.0 pts

Broncos penalties, every game · Bears penalties, every game · All teams, 2023

When it happened

Bears’ chance of winning

As low as 0% and as high as 98%. 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 Bears were ahead in it, below while the Broncos were.
#WhenWhat happenedWin probability forNext drive
1 Q4 7:05 The game turned hereThe Bears fumbled and the Broncos recoveredFumble bounces · loose balls are close to 50/50Return touchdown by the BroncosSpecial teams +50% DEN CHI: Turnover on downs
2 Q4 5:49 The Bears converted 3rd & 103rd & 4th downs · 29% expectedFalse Start on the Bears, 5 yardsPre-snap flags +9% CHI CHI: Turnover on downs
3 Q4 2:57 The Bears were stopped on 4th & 13rd & 4th downs · 76% expected +12% DEN CHI: Turnover
4 Q4 1:55 C. Sutton dropped a catchable passDrops · 3 drops on 97 catchable balls before this +23% CHI DEN: Field goal
5 Q4 1:51 W. Lutz made a 51-yard field goalKicks · 68% expected for him, 23 of 35 from 45+ before +13% DEN DEN: End of game
6 Q4 1:14 The Bears converted 3rd & 103rd & 4th downs · 29% expected +9% CHI CHI: Turnover
7 Q4 0:50 Intentional Grounding on the Bears (Justin Fields), 11 yardsJudgment calls · 3 flags in 1730 snaps before, position avg 1 per 643 +13% DEN DEN: End of game
8 Q4 0:38 The Bears threw an interception-worthy pass, and it was pickedInterceptions · defenses catch 49% of interception-worthy throws +38% DEN –

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.

  • Jaylon Johnson (CHI CB), out · 0.9 pts
  • Chase Claypool (CHI WR), out · 0.7 pts
  • Braxton Jones (CHI T), out (IR) · 0.7 pts
  • Kyler Gordon (CHI CB), out (IR) · 0.7 pts
  • Eddie Jackson (CHI FS), out · 0.5 pts
  • Justin Simmons (DEN FS), out · 0.9 pts
  • Josey Jewell (DEN LB), out · 0.4 pts
  • K'Waun Williams (DEN CB), out (IR) · 0.4 pts
  • Greg Dulcich (DEN TE), out (IR) · 0.3 pts
  • Baron Browning (DEN LB), 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

Broncos 35% · Bears 65%

Final margin
Broncos by 3
Luck in points
5.9 for the Broncos
Luck-adjusted margin
Bears by 2.9
Replay with same day's form
Broncos 48% · Bears 52% unchanged: why
How much of each is luck?

0% treats it as skill, 100% as pure luck. The tick is our fit.

What counts

None by default: our tests measured no carryover after a lucky break. Slide it up to count a break for more than its own swing. 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 4 2023 games · Broncos · Bears

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