luckadjusted
NFL Week 9 · 2026

Week 14 2023 · December 10, 2023

Lions at Bears, Week 14 2023: who deserved to win?

The Bears beat the Lions 28–13, and the replays back it up: with the way both teams actually played, the Bears win 9 of 10.

An off day for the Lions: their offense played far below its usual level. In a fresh game against the Bears they would win 55% of the time; with this day’s form, 5%. The numbers

Before kickoff the Lions were 59% favorites. The biggest swing (Q3, 1:42 left): the Bears converted 4th & 13, worth 16 points of win probability to the Bears.

Final

Detroit Lions 13
Chicago Bears 28

December 10, 2023 · Soldier Field · Closing line: Lions −3

Luck index +5 Bears about even · −5 Lions

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. Lions win 1, Bears win 9.

  1. 1 DET 34 CHI 26
  2. 2 DET 14 CHI 16
  3. 3 DET 16 CHI 20
  4. 4 DET 21 CHI 29
  5. 5 DET 17 CHI 28
  6. 6 DET 26 CHI 40
  7. 7 DET 6 CHI 22
  8. 8 DET 17 CHI 37
  9. 9 DET 6 CHI 30
  10. 10 DET 10 CHI 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.

An off day for the Lions

Their offense played far below its usual level. In a fresh game against the Bears they would win 55% of the time; with this day’s form, 5%.

49 points apart for the Lions: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Lions offenseEPA per play gained +0.01 +0.15 worse by 0.14
Lions defenseEPA per play allowed +0.10 +0.11 better by 0.02
Bears offenseEPA per play gained +0.10 +0.09 better by 0.01
Bears defenseEPA per play allowed +0.01 +0.15 better by 0.14

EPA (expected points added) per play on competitive snaps, turnovers left out because they are valued as luck. Usual level: the team’s earlier games this season plus half of last season, pulled toward the league average. One team’s defense and the other team’s offense are the same snaps, so one game can’t fully say whose day it was; it shows how far this one was from both teams’ norms.

How 4,000 replays ended

Lions win 5% of them, Bears 95%, counting the 1% still level after regulation as half each. The line is what actually happened: Bears by 15.

Show as a table
Final margin in the replaysShare of replays
Lions by 17+0.1%
Lions by 9–160.9%
Lions by 1–83.8%
Level after regulation0.9%
Bears by 1–88.6%
Bears by 9–1622.5%
Bears by 17+63.2%

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 +9.5 points to the Bears: the final margin was Bears by 15, without the luck Bears by 5.5. Luck shares are the fitted ones (how much of each kind is luck).

The kicks

How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.

  • C. Santos, 46 yds made · 73% expected
  • C. Santos, 25 yds made · 97% expected
  • C. Santos, 28 yds made · 96% expected
  • Extra point missed · 94% expected
  • Extra point missed · 94% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Lions 8 for 59 yards, Bears 4 for 35 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 7:44 Tripping on the Lions, 15 yards +3% CHI +1.5 pts
Q1 3:54 Defensive Holding on the Lions (Alex Anzalone), 5 yards +1% CHI +0.7 pts
Q1 3:25 Unnecessary Roughness on the Lions (Alex Anzalone), 15 yards +3% CHI +1.8 pts
Q1 0:01 Delay of Game on the Lions, 5 yards · pre-snap +3% CHI +0.7 pts
Q2 14:12 Illegal Block Above the Waist on the Bears (Eddie Jackson), 10 yards +2% DET +0.9 pts
Q2 9:44 False Start on the Lions, 5 yards · pre-snap +3% CHI +0.9 pts
Q3 10:20 Defensive Pass Interference on the Lions (Jerry Jacobs), 4 yards 0% DET +0.1 pts
Q3 8:38 False Start on the Lions, 5 yards · pre-snap +3% CHI +0.8 pts
Q3 7:36 Offensive Holding on the Bears, 10 yards, wiping out the play +12% DET +3.1 pts
Q4 6:12 False Start on the Lions, 5 yards · pre-snap 0% CHI +0.6 pts
Q4 4:31 Offensive Holding on the Bears, 10 yards 0% DET +1.2 pts
Q4 2:44 Defensive Offside on the Bears (Rasheem Green), 5 yards · pre-snap 0% CHI 0.0 pts

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

When it happened

Bears’ chance of winning

As low as 33% 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 Bears were ahead in it, below while the Lions were.
#WhenWhat happenedWin probability forNext drive
1 Q1 1:27 C. Santos made a 46-yard field goalKicks · 73% expected for him, 24 of 34 from 45+ before +6% CHI CHI: Turnover on downs
2 Q2 9:01 The Lions converted 4th & 33rd & 4th downs · 55% expected +7% DET DET: Touchdown
3 Q2 3:54 The Lions converted 3rd & 23rd & 4th downs · 63% expected +7% DET DET: Touchdown
4 Q3 10:38 The Bears converted 3rd & 83rd & 4th downs · 34% expected +9% CHI CHI: Field goal
5 Q3 7:36 Offensive Holding on the Bears, 10 yards, wiping out the playJudgment calls +12% DET DET: Punt
6 Q3 3:26 The Bears converted 3rd & 33rd & 4th downs · 55% expected +8% CHI CHI: Touchdown
7 Q3 1:42 The Bears converted 4th & 133rd & 4th downs · 26% expected +16% CHI CHI: Touchdown
8 Q4 14:19 The Bears converted 3rd & 113rd & 4th downs · 29% expected +6% 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.

  • Frank Ragnow (DET C), out · 0.8 pts
  • Alim McNeill (DET DT), out (IR) · 0.3 pts
  • Scott Daly (DET LS), out (IR) · 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

Lions 9% · Bears 91%

Final margin
Bears by 15
Luck in points
9.5 for the Bears
Luck-adjusted margin
Bears by 5.5
Replay with same day's form
Lions 5% · Bears 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

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 14 2023 games · Lions · Bears

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