luckadjusted
NFL Week 9 · 2026

Week 18 2025 · January 4, 2026

Lions at Bears, Week 18 2025: who deserved to win?

The Lions beat the Bears 19–16, and the replays lean their way: with the same day's form, they win 8 of 10.

An off day for the Bears: they played far below what the matchup promised. In a fresh game against the Lions they would win 56% of the time; with this day’s form, 20%. The numbers

Before kickoff the Bears were 60% favorites. The biggest swing (Q4, 0:02 left): J. Bates made a 42-yard field goal, worth 16 points of win probability to the Lions.

Final

Detroit Lions 19
Chicago Bears 16

January 4, 2026 · Soldier Field · Closing line: Bears −3.5

Luck index +20 Lions about even · −20 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. Lions win 8, Bears win 2.

  1. 1 DET 31 CHI 3
  2. 2 DET 38 CHI 17
  3. 3 DET 24 CHI 7
  4. 4 DET 14 CHI 0
  5. 5 DET 22 CHI 12
  6. 6 DET 20 CHI 14
  7. 7 DET 34 CHI 30
  8. 8 DET 23 CHI 21
  9. 9 DET 13 CHI 17
  10. 10 DET 10 CHI 22

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 Bears

They played far below what the matchup promised. In a fresh game against the Lions they would win 56% of the time; with this day’s form, 20%.

35 points apart for the Bears: 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 +0.22 +0.17 better by 0.05
Lions defenseEPA per play allowed +0.06 +0.10 better by 0.04
Bears offenseEPA per play gained +0.06 +0.09 worse by 0.03
Bears defenseEPA per play allowed +0.22 +0.14 worse by 0.08

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 80% of them, Bears 20%, counting the 5% still level after regulation as half each. The line is what actually happened: Lions by 3.

Show as a table
Final margin in the replaysShare of replays
Lions by 17+24.7%
Lions by 9–1623.5%
Lions by 1–827.0%
Level after regulation4.6%
Bears by 1–812.9%
Bears by 9–165.2%
Bears by 17+2.2%

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 +5.6 points to the Bears: the final margin was Lions by 3, without the luck Lions by 8.6. 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.

  • J. Bates, 34 yds made · 93% expected
  • J. Bates, 30 yds made · 96% expected
  • J. Bates, 53 yds missed · 65% expected
  • J. Bates, 25 yds made · 98% expected
  • J. Bates, 42 yds made · 84% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Lions 6 for 35 yards, Bears 4 for 25 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
Q2 14:09 Offensive Holding on the Lions, 10 yards +3% CHI +1.6 pts
Q2 7:38 Encroachment on the Bears (Andrew Billings), 5 yards · pre-snap +4% DET +1.7 pts
Q3 11:41 Delay of Game on the Lions, 5 yards · pre-snap +2% CHI +0.8 pts
Q3 8:36 Defensive Offside on the Lions (Roy Lopez), 5 yards · pre-snap +4% CHI +2.9 pts
Q3 8:28 False Start on the Bears (D.J. Moore), 5 yards · pre-snap 0% DET +0.5 pts
Q4 15:00 Neutral Zone Infraction on the Lions (Tyler Lacy), 5 yards · pre-snap +1% CHI +0.5 pts
Q4 5:51 Defensive Holding on the Lions (Mekhi Wingo), 0 yards +1% CHI +0.4 pts
Q4 2:30 Encroachment on the Bears (Andrew Billings), 5 yards · pre-snap +1% DET +0.2 pts
Q4 2:26 Intentional Grounding on the Lions (Jared Goff), 10 yards +4% CHI +0.9 pts
Q4 2:07 Intentional Grounding on the Bears (Caleb Williams), 10 yards +6% DET +0.8 pts

Lions penalties, every game · Bears penalties, every game · All teams, 2025

When it happened

Bears’ chance of winning

As low as 0% and as high as 64%. 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 8:46 A. St. Brown dropped a catchable passDrops · 18 drops on 515 catchable balls before this +7% CHI DET: Field goal
2 Q1 1:00 The Lions converted 3rd & 93rd & 4th downs · 33% expected +8% DET DET: Field goal
3 Q4 5:25 The Bears’ two-point try was good3rd & 4th downs · 47% expected +12% CHI CHI: Punt
4 Q4 4:37 The Lions converted 3rd & 73rd & 4th downs · 38% expected +9% DET DET: Turnover
5 Q4 3:20 The Lions converted 3rd & 13rd & 4th downs · 77% expected +9% DET DET: Turnover
6 Q4 2:23 The Lions threw an interception-worthy pass, and it was pickedInterceptions · defenses catch 55% of interception-worthy throws +11% CHI DET: Field goal
7 Q4 2:11 L. Burden dropped a catchable passDrops · 5 drops on 53 catchable balls before this +7% DET CHI: Punt
8 Q4 0:02 J. Bates made a 42-yard field goalKicks · 84% expected for him +16% DET –

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.

  • Rome Odunze (CHI WR), out · 0.6 pts
  • Ozzy Trapilo (CHI OL), out · 0.3 pts
  • Penei Sewell (DET T), out · 1.6 pts
  • Brian Branch (DET DB), out (IR) · 0.8 pts
  • Alim McNeill (DET DL), out · 0.5 pts
  • Brock Wright (DET TE), out (IR) · 0.4 pts
  • Thomas Harper (DET S), out · 0.4 pts
  • Kayode Awosika (DET G), out · 0.3 pts
  • Alex Anzalone (DET LB), out · 0.3 pts
  • Trystan Colon (DET OL), 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

Lions 89% · Bears 11%

Final margin
Lions by 3
Luck in points
5.6 for the Bears
Luck-adjusted margin
Lions by 8.6
Replay with same day's form
Lions 80% · Bears 20% 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 18 2025 games · Lions · Bears

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