luckadjusted
NFL Week 9 · 2026

Week 13 2021 · December 5, 2021

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

Cardinals at Bears, Week 13 2021: who deserved to win?

The Cardinals beat the Bears 33–22, but the replays call it close to a coin flip: with the way both teams played, the Cardinals win 6 of 10.

Before kickoff the Cardinals were 71% favorites. The biggest swing (Q4, 11:55 left): Roughing the Kicker on the Cardinals, 15 yards, worth 8 points of win probability to the Bears.

Final

Arizona Cardinals 33
Chicago Bears 22

December 5, 2021 · Soldier Field · Closing line: Cardinals −7.5

Luck index +44 Cardinals lucky · −44 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. Cardinals win 6, Bears win 4.

  1. 1 ARI 27 CHI 3
  2. 2 ARI 22 CHI 7
  3. 3 ARI 27 CHI 17
  4. 4 ARI 27 CHI 20
  5. 5 ARI 17 CHI 13
  6. 6 ARI 23 CHI 21
  7. 7 ARI 23 CHI 26
  8. 8 ARI 17 CHI 23
  9. 9 ARI 10 CHI 20
  10. 10 ARI 17 CHI 35

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

Cardinals win 56% of them, Bears 44%, counting the 3% still level after regulation as half each. The line is what actually happened: Cardinals by 11.

Show as a table
Final margin in the replaysShare of replays
Cardinals by 17+12.5%
Cardinals by 9–1616.5%
Cardinals by 1–827.4%
Level after regulation2.8%
Bears by 1–821.9%
Bears by 9–1612.8%
Bears by 17+6.0%

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 +3.8 points to the Bears: the final margin was Cardinals by 11, without the luck Cardinals by 14.8. 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, 33 yds made · 92% expected
  • M. Prater, 25 yds made · 96% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Cardinals 8 for 63 yards, Bears 6 for 45 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 9:43 Unnecessary Roughness on the Cardinals (Byron Murphy), 15 yards +2% CHI +0.9 pts
Q1 1:47 False Start on the Cardinals (Zach Ertz), 5 yards · pre-snap +1% CHI +0.7 pts
Q2 4:09 Offensive Holding on the Bears (Cole Kmet), 10 yards +1% ARI +0.9 pts
Q2 3:36 Offensive Holding on the Cardinals (Robert Alford), 10 yards +1% CHI +0.9 pts
Q2 2:39 Delay of Game on the Cardinals, 5 yards · pre-snap +1% CHI +0.6 pts
Q2 1:21 Delay of Game on the Bears, 5 yards · pre-snap +1% ARI +0.3 pts
Q3 8:18 Illegal Use of Hands on the Cardinals (Byron Murphy), 5 yards, wiping out the play +1% CHI +1.2 pts
Q3 8:18 False Start on the Bears (Damiere Byrd), 5 yards · pre-snap +1% ARI +0.8 pts
Q3 6:21 Ineligible Downfield Pass on the Bears, 5 yards +2% ARI +0.8 pts
Q3 4:04 Defensive Holding on the Cardinals (Marco Wilson), 3 yards +1% CHI +0.4 pts
Q3 1:25 Defensive Pass Interference on the Bears (Xavier Crawford), 15 yards +4% ARI +2.2 pts
Q4 15:00 False Start on the Cardinals, 5 yards · pre-snap +2% CHI +0.8 pts
Q4 11:55 Roughing the Kicker on the Cardinals, 15 yards +8% CHI +3.7 pts
Q4 7:25 False Start on the Bears, 5 yards · pre-snap 0% ARI +0.6 pts

Cardinals penalties, every game · Bears penalties, every game · All teams, 2021

When it happened

Bears’ chance of winning

As low as 0% and as high as 55%. 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 Cardinals were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:35 The Cardinals fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +6% ARI ARI: Touchdown
2 Q1 11:02 The Cardinals converted 4th & 23rd & 4th downs · 63% expected +5% ARI ARI: Touchdown
3 Q1 9:19 The Bears fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +6% CHI CHI: Turnover
4 Q1 2:35 The Cardinals fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +4% ARI ARI: Touchdown
5 Q2 11:14 The Bears converted 4th & 83rd & 4th downs · 29% expected +5% CHI CHI: Touchdown
6 Q2 9:19 The Bears converted 3rd & 53rd & 4th downs · 38% expected +5% CHI CHI: Touchdown
7 Q3 1:25 Defensive Pass Interference on the Bears (Xavier Crawford), 15 yardsJudgment calls · 2 flags in 344 snaps before, position avg 1 per 213 +4% ARI ARI: Punt
8 Q4 11:55 Roughing the Kicker on the Cardinals, 15 yardsJudgment calls +8% CHI 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.

  • Allen Robinson (CHI WR), out · 0.7 pts
  • Germain Ifedi (CHI T), out (IR) · 0.6 pts
  • Khalil Mack (CHI LB), out (IR) · 0.6 pts
  • Duke Shelley (CHI CB), out (IR) · 0.2 pts
  • J.J. Watt (ARI DE), out (IR) · 1.2 pts
  • Justin Pugh (ARI G), out · 0.4 pts
  • Chase Edmonds (ARI RB), out (IR) · 0.1 pts
  • Aaron Brewer (ARI LS), out (IR) · 0.1 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

Cardinals 100% · Bears 0%

Final margin
Cardinals by 11
Luck in points
3.8 for the Bears
Luck-adjusted margin
Cardinals by 14.8
Replay with same day's form
Cardinals 56% · Bears 44% 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 13 2021 games · Cardinals · Bears

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