luckadjusted

Week 12 2021 · November 25, 2021

No FTN charting for this game (drops and interception-worthy throws are not modelled).

Bears at Lions, Week 12 2021: who deserved to win?

The Bears beat the Lions 16–14, and it was no fluke: replayed with the way both teams actually played, the Bears win 8 of 10. The Lions had the bounces: kicks alone were worth 2.3 points to the Lions.

Before kickoff the Bears were 56% favorites. The biggest swing (Q4, 0:01 left): C. Santos made 28-yard field goal, worth 42 points of win probability to the Bears.

Final

Chicago Bears 16
Detroit Lions 14

November 25, 2021 · Ford Field · Closing line: Bears −2

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

  1. 1 CHI 31 DET 0
  2. 2 CHI 36 DET 16
  3. 3 CHI 26 DET 10
  4. 4 CHI 20 DET 7
  5. 5 CHI 16 DET 7
  6. 6 CHI 17 DET 10
  7. 7 CHI 7 DET 3
  8. 8 CHI 12 DET 10
  9. 9 CHI 7 DET 10
  10. 10 CHI 21 DET 34

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 80% of them, Lions 20%, counting the 2% still level after regulation as half each. The line is what actually happened: Bears by 2.

Show as a table
Final margin in the replaysShare of replays
Bears by 17+28.5%
Bears by 9–1622.0%
Bears by 1–829.2%
Level after regulation2.4%
Lions by 1–810.8%
Lions by 9–165.5%
Lions by 17+1.6%

Where the luck was

Take the luck out

The final margin was Bears by 2. Remove the luck, one kind at a time, and it becomes Bears by 4.6.

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, 28 yds made · 97% expected
  • C. Santos, 43 yds made · 85% expected
  • C. Santos, 53 yds missed · 68% expected
  • C. Santos, 28 yds made · 97% 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 0% and as high as 80%. 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 9:33 The Lions converted 3rd & 103rd & 4th downs · 25% expected +11% DET DET: Touchdown
2 Q2 1:52 The Bears were stopped on 3rd & 103rd & 4th downs · 26% expected +11% DET CHI: Field goal
3 Q2 0:43 The Bears fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +8% CHI CHI: Field goal
4 Q3 11:47 The Bears converted 3rd & 123rd & 4th downs · 23% expected +8% CHI CHI: Missed field goal
5 Q4 14:55 The Bears converted 3rd & 73rd & 4th downs · 32% expected +9% CHI CHI: Punt
6 Q4 6:33 The Bears converted 3rd & 53rd & 4th downs · 39% expected +10% CHI CHI: Field goal
7 Q4 1:54 The Bears converted 3rd & 43rd & 4th downs · 44% expectedDefensive Delay of Game on the Lions, 5 yardsPre-snap flags +20% CHI CHI: Field goal
8 Q4 0:01 C. Santos made 28-yard field goalKicks · 97% expected for him +42% CHI –

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.

  • Matt Nelson (DET T), out · 0.6 pts
  • Frank Ragnow (DET C), out (IR) · 0.5 pts
  • Quintez Cephus (DET WR), out (IR) · 0.3 pts
  • Halapoulivaati Vaitai (DET G), out · 0.3 pts
  • Trey Flowers (DET LB), out · 0.3 pts
  • Austin Seibert (DET K), out (IR) · 0.2 pts
  • Romeo Okwara (DET LB), out (IR) · 0.2 pts
  • Germain Ifedi (CHI T), out (IR) · 0.8 pts
  • Allen Robinson (CHI WR), out · 0.7 pts
  • Khalil Mack (CHI LB), out (IR) · 0.5 pts
  • Duke Shelley (CHI CB), 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

Bears 80% · Lions 20%

Final margin
Bears by 2
Luck in points
2.6 for the Lions
Luck-adjusted margin
Bears by 4.6
Replay with same day's form
Bears 80% · Lions 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

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 (not available for this game); injuries from snap counts and injury reports. No FTN charting for this game (drops and interception-worthy throws are not modelled).

Methodology and validation · All Week 12 2021 games · Bears · Lions

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