luckadjusted

Week 18 2021 · January 9, 2022

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

Bears at Vikings, Week 18 2021: who deserved to win?

The Vikings beat the Bears 31–17, but it was a coin flip: replayed with the way both teams played, the Vikings win 5 of 10. Luck ran their way: 3rd & 4th downs alone were worth 4.4 points to the Vikings.

Before kickoff the Vikings were 60% favorites. The biggest swing (Q4, 13:44 left): the Vikings converted 3rd & 2, worth 28 points of win probability to the Vikings.

Final

Chicago Bears 17
Minnesota Vikings 31

January 9, 2022 · U.S. Bank Stadium · Closing line: Vikings −3.5

Luck index +46 Vikings lucky · −46 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 5, Vikings win 5.

  1. 1 CHI 35 MIN 14
  2. 2 CHI 24 MIN 10
  3. 3 CHI 19 MIN 10
  4. 4 CHI 23 MIN 17
  5. 5 CHI 16 MIN 14
  6. 6 CHI 17 MIN 20
  7. 7 CHI 20 MIN 26
  8. 8 CHI 13 MIN 23
  9. 9 CHI 9 MIN 23
  10. 10 CHI 5 MIN 28

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 46% of them, Vikings 54%, counting the 6% still level after regulation as half each. The line is what actually happened: Vikings by 14.

Show as a table
Final margin in the replaysShare of replays
Bears by 17+9.3%
Bears by 9–1613.6%
Bears by 1–822.1%
Level after regulation5.6%
Vikings by 1–822.3%
Vikings by 9–1615.9%
Vikings by 17+11.3%

Where the luck was

Take the luck out

The final margin was Vikings by 14. Remove the luck, one kind at a time, and it becomes Vikings by 16.4.

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, 43 yds made · 85% expected
  • C. Santos, 46 yds made · 78% expected
  • G. Joseph, 39 yds made · 90% expected
  • C. Santos, 42 yds made · 86% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Vikings’ chance of winning

As low as 16% 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 Vikings were ahead in it, below while the Bears were.
#WhenWhat happenedWin probability forNext drive
1 Q1 8:19 The Bears converted 4th & 13rd & 4th downs · 70% expected +9% CHI CHI: Turnover on downs
2 Q1 6:03 The Bears were stopped on 4th & 53rd & 4th downs · 37% expected +8% MIN CHI: Turnover on downs
3 Q3 12:31 The Vikings converted 3rd & 133rd & 4th downs · 22% expected +18% MIN MIN: Touchdown
4 Q3 7:55 The Bears were stopped on 4th & 13rd & 4th downs · 63% expected +15% MIN CHI: Field goal
5 Q3 0:28 The Vikings converted 3rd & 73rd & 4th downs · 32% expected +8% MIN MIN: Touchdown
6 Q4 13:44 The Vikings converted 3rd & 23rd & 4th downs · 59% expected +28% MIN MIN: Touchdown
7 Q4 10:08 The Vikings converted 3rd & 43rd & 4th downs · 44% expected +8% MIN MIN: Touchdown
8 Q4 5:10 The Bears were stopped on 4th & 13rd & 4th downs · 70% expectedReturn touchdown by the VikingsSpecial teams +21% MIN CHI: Turnover

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.

  • Everson Griffen (MIN DE), out (IR) · 0.9 pts
  • Adam Thielen (MIN WR), out (IR) · 0.6 pts
  • Eric Kendricks (MIN LB), out (IR) · 0.5 pts
  • Mason Cole (MIN C), out (IR) · 0.5 pts
  • Mackensie Alexander (MIN CB), out · 0.3 pts
  • Akiem Hicks (CHI DT), out · 0.3 pts
  • Duke Shelley (CHI CB), out · 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% · Vikings 100%

Final margin
Vikings by 14
Luck in points
2.4 for the Bears
Luck-adjusted margin
Vikings by 16.4
Replay with same day's form
Bears 46% · Vikings 54% 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 18 2021 games · Bears · Vikings

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