luckadjusted

Week 17 2022 · January 1, 2023

Bears at Lions, Week 17 2022: who deserved to win?

The Lions beat the Bears 41–10, and it was no fluke: replayed with the way both teams actually played, the Lions win 10 of 10.

An off day for the Bears: their defense played far below its usual level. In a fresh game against the Lions they would win 33% of the time; with this day’s form, 1%. The numbers

Before kickoff the Lions were 63% favorites. The biggest swing (Q1, 5:21 left): the Bears converted 3rd & 4, worth 18 points of win probability to the Bears.

Final

Chicago Bears 10
Detroit Lions 41

January 1, 2023 · Ford Field · Closing line: Lions −4.5

Luck index +1 Lions 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, Lions win 10.

  1. 1 CHI 26 DET 31
  2. 2 CHI 10 DET 20
  3. 3 CHI 20 DET 34
  4. 4 CHI 13 DET 30
  5. 5 CHI 10 DET 30
  6. 6 CHI 20 DET 43
  7. 7 CHI 12 DET 38
  8. 8 CHI 13 DET 44
  9. 9 CHI 6 DET 41
  10. 10 CHI 0 DET 43

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

Their defense played far below its usual level. In a fresh game against the Lions they would win 33% of the time; with this day’s form, 1%.

32 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
Bears offenseEPA per play gained +0.17 +0.07 better by 0.10
Bears defenseEPA per play allowed +0.34 +0.17 worse by 0.18
Lions offenseEPA per play gained +0.34 +0.10 better by 0.24
Lions defenseEPA per play allowed +0.17 +0.18 better by 0.01

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

Bears win 1% of them, Lions 99%. The line is what actually happened: Lions by 31.

Show as a table
Final margin in the replaysShare of replays
Bears by 17+0.0%
Bears by 9–160.1%
Bears by 1–80.4%
Level after regulation0.1%
Lions by 1–81.8%
Lions by 9–168.0%
Lions by 17+89.5%

Where the luck was

Take the luck out

The final margin was Lions by 31. Remove the luck, one kind at a time, and it becomes Lions by 19.8.

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).

The kicks

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

  • C. Santos, 23 yds made · 99% expected
  • M. Badgley, 23 yds made · 97% expected
  • M. Badgley, 41 yds made · 86% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Lions’ chance of winning

As low as 37% 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 Lions were ahead in it, below while the Bears were.
#WhenWhat happenedWin probability forNext drive
1 Q1 12:26 The Bears converted 3rd & 13rd & 4th downs · 72% expected +9% CHI CHI: Touchdown
2 Q1 11:00 The Bears converted 3rd & 23rd & 4th downs · 58% expected +6% CHI CHI: Touchdown
3 Q1 9:35 The Lions converted 3rd & 43rd & 4th downs · 48% expected +5% DET DET: Touchdown
4 Q1 7:38 Defensive Pass Interference on the Bears, 34 yardsJudgment calls +14% DET DET: Touchdown
5 Q1 5:21 The Bears converted 3rd & 43rd & 4th downs · 43% expected +18% CHI CHI: Field goal
6 Q1 3:06 The Bears were stopped on 3rd & 23rd & 4th downs · 50% expected +7% DET CHI: Field goal
7 Q1 2:28 C. Santos made 23-yard field goalKicks · 99% expected for him +5% DET CHI: Punt
8 Q2 9:47 The Bears were stopped on 3rd & 63rd & 4th downs · 35% expected +8% DET CHI: Punt

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.

  • DeShon Elliott (DET FS), out · 0.4 pts
  • Jaylon Johnson (CHI CB), out (IR) · 0.9 pts
  • Trevor Siemian (CHI QB), out (IR), replaced by j.fields · 0.9 pts
  • Darnell Mooney (CHI WR), out (IR) · 0.8 pts
  • Eddie Jackson (CHI SS), out (IR) · 0.8 pts
  • Jack Sanborn (CHI LB), out (IR) · 0.3 pts
  • Kindle Vildor (CHI CB), out (IR) · 0.3 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% · Lions 100%

Final margin
Lions by 31
Luck in points
11.2 for the Lions
Luck-adjusted margin
Lions by 19.8
Replay with same day's form
Bears 1% · Lions 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 17 2022 games · Bears · Lions

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