luckadjusted

Week 17 2023 · December 31, 2023

Falcons at Bears, Week 17 2023: who deserved to win?

The Bears beat the Falcons 37–17, and it was no fluke: replayed with the way both teams actually played, the Bears win 9 of 10. The Falcons had the bounces: judgment calls alone were worth 6.2 points to the Falcons.

Before kickoff the Bears were 59% favorites. The biggest swing (Q1, 12:24 left): Y. Koo missed 50-yard field goal, worth 8 points of win probability to the Bears.

Final

Atlanta Falcons 17
Chicago Bears 37

December 31, 2023 · Soldier Field · Closing line: Bears −3

Luck index +10 Bears about even · −10 Falcons

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. Falcons win 1, Bears win 9.

  1. 1 ATL 21 CHI 12
  2. 2 ATL 17 CHI 19
  3. 3 ATL 23 CHI 29
  4. 4 ATL 17 CHI 26
  5. 5 ATL 24 CHI 36
  6. 6 ATL 14 CHI 30
  7. 7 ATL 14 CHI 33
  8. 8 ATL 17 CHI 40
  9. 9 ATL 5 CHI 32
  10. 10 ATL 6 CHI 40

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

Falcons win 10% of them, Bears 90%, counting the 1% still level after regulation as half each. The line is what actually happened: Bears by 20.

Show as a table
Final margin in the replaysShare of replays
Falcons by 17+1.0%
Falcons by 9–162.8%
Falcons by 1–86.0%
Level after regulation1.1%
Bears by 1–814.9%
Bears by 9–1620.5%
Bears by 17+53.7%

Where the luck was

Take the luck out

The final margin was Bears by 20. Remove the luck, one kind at a time, and it becomes Bears by 20.3.

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.

  • Y. Koo, 50 yds missed · 73% expected
  • Y. Koo, 42 yds missed · 84% expected
  • C. Santos, 55 yds missed · 61% expected
  • C. Santos, 22 yds made · 99% expected
  • Y. Koo, 38 yds made · 89% expected
  • C. Santos, 42 yds made · 83% expected
  • C. Santos, 42 yds made · 83% 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 47% 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 Bears were ahead in it, below while the Falcons were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:42 The Falcons fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +6% ATL ATL: Missed field goal
2 Q1 12:24 Y. Koo missed 50-yard field goalKicks · 73% expected for him, 45 of 55 from 45+ before +8% CHI ATL: Missed field goal
3 Q1 10:51 The Bears converted 3rd & 93rd & 4th downs · 31% expected +7% CHI CHI: Touchdown
4 Q1 8:52 The Bears converted 3rd & 73rd & 4th downs · 28% expected +6% CHI CHI: Touchdown
5 Q1 3:22 Y. Koo missed 42-yard field goalKicks · 84% expected for him +7% CHI ATL: Touchdown
6 Q2 9:47 The Bears converted 3rd & 83rd & 4th downs · 33% expected +5% CHI CHI: Touchdown
7 Q4 12:32 The Falcons converted 3rd & 53rd & 4th downs · 41% expected +6% ATL ATL: Touchdown
8 Q4 11:03 Offensive Holding on the Bears, 10 yards, wiping out the playJudgment calls +7% ATL ATL: Punt

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.

  • Darnell Mooney (CHI WR), out · 0.8 pts
  • Yannick Ngakoue (CHI DE), out (IR) · 0.7 pts
  • Kentavius Street (ATL DT), 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

Falcons 0% · Bears 100%

Final margin
Bears by 20
Luck in points
0.3 for the Falcons
Luck-adjusted margin
Bears by 20.3
Replay with same day's form
Falcons 10% · Bears 90% 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; injuries from snap counts and injury reports.

Methodology and validation · All Week 17 2023 games · Falcons · Bears

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