luckadjusted

Week 17 2020 · January 3, 2021

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

Packers at Bears, Week 17 2020: who deserved to win?

The Packers beat the Bears 35–16, and it was no fluke: replayed with the way both teams actually played, the Packers win 9 of 10.

Before kickoff the Packers were 63% favorites. The biggest swing (Q2, 8:40 left): the Packers converted 3rd & 4, worth 22 points of win probability to the Packers.

Final

Green Bay Packers 35
Chicago Bears 16

January 3, 2021 · Soldier Field · Closing line: Packers −4.5

Luck index +6 Packers about even · −6 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. Packers win 9, Bears win 1.

  1. 1 GB 41 CHI 10
  2. 2 GB 44 CHI 20
  3. 3 GB 31 CHI 10
  4. 4 GB 28 CHI 10
  5. 5 GB 31 CHI 17
  6. 6 GB 31 CHI 20
  7. 7 GB 16 CHI 7
  8. 8 GB 27 CHI 21
  9. 9 GB 20 CHI 17
  10. 10 GB 21 CHI 27

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

Packers win 94% of them, Bears 6%, counting the 2% still level after regulation as half each. The line is what actually happened: Packers by 19.

Show as a table
Final margin in the replaysShare of replays
Packers by 17+53.9%
Packers by 9–1622.4%
Packers by 1–815.8%
Level after regulation1.6%
Bears by 1–84.6%
Bears by 9–161.4%
Bears by 17+0.3%

Where the luck was

Take the luck out

The final margin was Packers by 19. Remove the luck, one kind at a time, and it becomes Packers 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, 30 yds made · 95% expected
  • C. Santos, 27 yds made · 97% expected
  • C. Santos, 20 yds made · 99% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Bears’ chance of winning

As low as 0% and as high as 73%. 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 Packers were.
#WhenWhat happenedWin probability forNext drive
1 Q1 9:57 The Bears converted 4th & 33rd & 4th downs · 47% expected +10% CHI CHI: Touchdown
2 Q1 0:33 Defensive Pass Interference on the Bears (Duke Shelley), 16 yardsJudgment calls · 3 flags in 313 snaps before, position avg 1 per 237 +8% GB GB: Touchdown
3 Q2 12:33 The Packers fumbled and the Bears recoveredFumble bounces · loose balls are close to 50/50 +8% CHI GB: Touchdown
4 Q2 8:40 The Packers converted 3rd & 43rd & 4th downs · 50% expected +22% GB GB: Touchdown
5 Q3 0:41 The Bears converted 4th & 13rd & 4th downs · 69% expected +8% CHI CHI: Turnover on downs
6 Q4 13:26 The Bears converted 4th & 13rd & 4th downs · 69% expected +10% CHI CHI: Turnover on downs
7 Q4 12:01 The Bears were stopped on 3rd & 13rd & 4th downs · 70% expected +8% GB CHI: Turnover on downs
8 Q4 11:27 The Bears were stopped on 4th & 13rd & 4th downs · 69% expected +15% GB 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.

  • Jaylon Johnson (CHI DB), out · 0.7 pts
  • Buster Skrine (CHI DB), out · 0.4 pts
  • David Bakhtiari (GB T), out (IR) · 1.4 pts
  • Raven Greene (GB S), 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

Packers 100% · Bears 0%

Final margin
Packers by 19
Luck in points
0.8 for the Bears
Luck-adjusted margin
Packers by 19.8
Replay with same day's form
Packers 94% · Bears 6% 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 17 2020 games · Packers · Bears

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