luckadjusted
NFL Week 9 · 2026

Week 17 2023 · December 30, 2023

Lions at Cowboys, Week 17 2023: who deserved to win?

The Cowboys beat the Lions 20–19, but the replays lean toward the Lions: they take 7 of 10 with the same day's form. Luck ran their way: 3rd & 4th downs alone were worth 19 points of win probability to the Cowboys.

Before kickoff the Cowboys were 66% favorites. The biggest swing (Q4, 0:23 left): the Lions’ two-point try failed, worth 20 points of win probability to the Cowboys.

Final

Detroit Lions 19
Dallas Cowboys 20

December 30, 2023 · AT&T Stadium · Closing line: Cowboys −5.5

Luck index +66 Cowboys very lucky · −66 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. Lions win 7, Cowboys win 3.

  1. 1 DET 44 DAL 13
  2. 2 DET 34 DAL 13
  3. 3 DET 23 DAL 7
  4. 4 DET 34 DAL 23
  5. 5 DET 34 DAL 26
  6. 6 DET 31 DAL 27
  7. 7 DET 25 DAL 23
  8. 8 DET 10 DAL 13
  9. 9 DET 26 DAL 34
  10. 10 DET 10 DAL 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

Lions win 66% of them, Cowboys 34%, counting the 2% still level after regulation as half each. The line is what actually happened: Cowboys by 1.

Show as a table
Final margin in the replaysShare of replays
Lions by 17+19.7%
Lions by 9–1619.2%
Lions by 1–825.0%
Level after regulation2.3%
Cowboys by 1–818.1%
Cowboys by 9–169.5%
Cowboys by 17+6.4%

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 +5.3 points to the Cowboys: the final margin was Cowboys by 1, without the luck Lions by 4.3. 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. Badgley, 41 yds made · 87% expected
  • B. Aubrey, 51 yds made · 76% expected
  • M. Badgley, 30 yds made · 95% expected
  • B. Aubrey, 43 yds made · 87% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Lions 6 for 35 yards, Cowboys 5 for 34 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 2:51 False Start on the Lions, 5 yards · pre-snap +1% DAL +0.6 pts
Q1 1:07 False Start on the Cowboys (Jake Ferguson), 5 yards · pre-snap +1% DET +0.7 pts
Q2 11:30 Defensive Offside on the Lions (Benito Jones), 5 yards · pre-snap +2% DAL +0.7 pts
Q2 2:02 Delay of Game on the Cowboys, 5 yards · pre-snap +1% DET +0.5 pts
Q3 14:26 False Start on the Cowboys, 5 yards · pre-snap +2% DET +0.9 pts
Q3 0:23 Offensive Holding on the Lions (James Mitchell), 10 yards +4% DAL +0.9 pts
Q4 12:21 Delay of Game on the Lions, 5 yards · pre-snap +4% DAL +0.2 pts
Q4 5:12 Illegal Contact on the Lions (Kindle Vildor), 5 yards +3% DAL +1.1 pts
Q4 2:05 Tripping on the Cowboys (Peyton Hendershot), 15 yards, wiping out the play +2% DET +1.6 pts
Q4 0:23 Illegal Touch Pass on the Lions, 5 yards 0% DAL 0.0 pts
Q4 0:23 Defensive Offside on the Cowboys (Micah Parsons), 4 yards · pre-snap 0% DET 0.0 pts

Lions penalties, every game · Cowboys penalties, every game · All teams, 2023

When it happened

Cowboys’ chance of winning

As low as 38% 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 Cowboys were ahead in it, below while the Lions were.
#WhenWhat happenedWin probability forNext drive
1 Q2 5:45 The Lions were stopped on 4th & 43rd & 4th downs · 40% expected +10% DAL DET: Punt
2 Q3 1:52 The Cowboys converted 3rd & 113rd & 4th downs · 28% expected +14% DAL DAL: Field goal
3 Q3 0:35 C. Lamb dropped a catchable passDrops · 9 drops on 262 catchable balls before this +8% DET DAL: Field goal
4 Q3 0:27 B. Aubrey made a 51-yard field goalKicks · 76% expected for him, 10 of 10 from 45+ before +9% DAL DAL: Touchdown
5 Q4 10:25 The Cowboys converted 3rd & 53rd & 4th downs · 43% expected +11% DAL DAL: Touchdown
6 Q4 4:19 The Cowboys converted 3rd & 103rd & 4th downs · 30% expected +9% DAL DAL: Punt
7 Q4 0:43 The Lions converted 3rd & 103rd & 4th downs · 29% expected +8% DET DET: Touchdown
8 Q4 0:23 The Lions’ two-point try failed3rd & 4th downs · 47% expectedIllegal Touch Pass on the Lions, 5 yardsJudgment callsDefensive Offside on the Cowboys (Micah Parsons), 4 yardsPre-snap flags · 14 flags in 2809 snaps before, position avg 1 per 444 +20% DAL DET: End of game

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.

  • Alim McNeill (DET DT), out (IR) · 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

Lions 78% · Cowboys 22%

Final margin
Cowboys by 1
Luck in points
5.3 for the Cowboys
Luck-adjusted margin
Lions by 4.3
Replay with same day's form
Lions 66% · Cowboys 34% 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; injuries from snap counts and injury reports.

Methodology and validation · All Week 17 2023 games · Lions · Cowboys

More from Week 17 2023