luckadjusted
NFL Week 9 · 2026

Week 1 2020 · September 13, 2020

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

Bears at Lions, Week 1 2020: who deserved to win?

The Bears beat the Lions 27–23, but the replays lean toward the Lions: they take 8 of 10 with the same day's form.

Before kickoff the Lions were 57% favorites. The biggest swing (Q4, 0:28 left): the Lions converted 3rd & 7, worth 22 points of win probability to the Lions.

Final

Chicago Bears 27
Detroit Lions 23

September 13, 2020 · Ford Field · Closing line: Lions −2.5

Luck index +76 Bears very lucky · −76 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 2, Lions win 8.

  1. 1 CHI 37 DET 23
  2. 2 CHI 27 DET 23
  3. 3 CHI 31 DET 33
  4. 4 CHI 17 DET 22
  5. 5 CHI 26 DET 34
  6. 6 CHI 16 DET 28
  7. 7 CHI 17 DET 33
  8. 8 CHI 16 DET 34
  9. 9 CHI 13 DET 34
  10. 10 CHI 7 DET 37

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 24% of them, Lions 76%, counting the 2% still level after regulation as half each. The line is what actually happened: Bears by 4.

Show as a table
Final margin in the replaysShare of replays
Bears by 17+3.3%
Bears by 9–167.0%
Bears by 1–813.3%
Level after regulation2.1%
Lions by 1–824.5%
Lions by 9–1620.6%
Lions by 17+29.1%

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 +5.0 points to the Bears: the final margin was Bears by 4, without the luck Lions by 1. 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.

  • M. Prater, 27 yds made · 97% expected
  • C. Santos, 35 yds made · 93% expected
  • M. Prater, 32 yds made · 96% expected
  • C. Santos, 28 yds made · 96% expected
  • M. Prater, 44 yds made · 84% expected
  • M. Prater, 55 yds missed · 69% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Bears 6 for 48 yards, Lions 8 for 77 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
Q1 8:53 Unnecessary Roughness on the Bears (Kyle Fuller), 15 yards +3% DET +1.2 pts
Q1 1:30 Offensive Holding on the Lions, 10 yards +2% CHI +1.4 pts
Q2 12:37 Disqualification on the Lions (Jamie Collins), 15 yards +5% CHI +1.8 pts
Q2 9:31 Offensive Holding on the Lions (T.J. Hockenson), 10 yards +5% CHI +1.3 pts
Q2 9:06 False Start on the Lions, 5 yards · pre-snap +1% CHI +0.3 pts
Q2 3:19 Face Mask on the Lions (Desmond Trufant), 12 yards +5% CHI +1.5 pts
Q2 0:51 Player Out of Bounds on Kick on the Bears (Cordarrelle Patterson), 5 yards 0% DET +0.4 pts
Q3 11:48 Roughing the Passer on the Bears, 7 yards +2% DET +1.0 pts
Q3 4:55 Defensive Holding on the Bears (Akiem Hicks), 5 yards +1% DET +0.8 pts
Q3 4:51 Defensive Pass Interference on the Bears (Buster Skrine), 11 yards 0% DET +0.7 pts
Q4 10:53 Delay of Game on the Lions, 5 yards · pre-snap 0% CHI +0.2 pts
Q4 10:44 Face Mask on the Lions, 15 yards +1% CHI +1.8 pts
Q4 9:28 Delay of Game on the Bears, 5 yards · pre-snap +2% DET +0.8 pts
Q4 2:00 Neutral Zone Infraction on the Lions (Jahlani Tavai), 5 yards · pre-snap +6% CHI +0.4 pts

Bears penalties, every game · Lions penalties, every game · All teams, 2020

When it happened

Lions’ chance of winning

As low as 0% and as high as 97%. 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 9:09 The Bears were stopped on 3rd & 73rd & 4th downs · 37% expected +5% DET CHI: Turnover on downs
2 Q2 12:37 Disqualification on the Lions (Jamie Collins), 15 yardsJudgment calls · 0 flags in 1055 snaps before, position avg 1 per 395 +5% CHI CHI: Punt
3 Q2 9:31 Offensive Holding on the Lions (T.J. Hockenson), 10 yardsJudgment calls · 5 flags in 527 snaps before, position avg 1 per 276 +5% CHI CHI: Field goal
4 Q2 9:06 The Lions converted 3rd & 173rd & 4th downs · 20% expectedFalse Start on the Lions, 5 yardsPre-snap flags +6% DET DET: Field goal
5 Q2 8:18 The Lions converted 3rd & 103rd & 4th downs · 29% expected +11% DET DET: Field goal
6 Q4 2:00 Neutral Zone Infraction on the Lions (Jahlani Tavai), 5 yardsPre-snap flags · 1 flag in 686 snaps before, position avg 1 per 395 +6% CHI CHI: Touchdown
7 Q4 0:28 The Lions converted 3rd & 73rd & 4th downs · 36% expected +22% DET DET: End of game
8 Q4 0:06 The Lions were stopped on 3rd & 103rd & 4th downs · 29% expected +15% 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.

  • Kenny Golladay (DET WR), out · 0.9 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 46% · Lions 54%

Final margin
Bears by 4
Luck in points
5.0 for the Bears
Luck-adjusted margin
Lions by 1.0
Replay with same day's form
Bears 24% · Lions 76% 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 (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 1 2020 games · Bears · Lions

More from Week 1 2020