luckadjusted

Week 17 2023 · December 31, 2023

Cardinals at Eagles, Week 17 2023: who deserved to win?

The Cardinals beat the Eagles 35–31, but it was a coin flip: replayed with the way both teams played, the Cardinals win 5 of 10. Luck ran their way: judgment calls alone were worth 5.0 points to the Cardinals.

An off day for the Eagles: their defense played far below its usual level. In a fresh game against the Cardinals they would win 80% of the time; with this day’s form, 47%. The numbers

Before kickoff the Eagles were 81% favorites. The biggest swing (Q2, 12:01 left): the Cardinals were stopped on 3rd & 7, worth 61 points of win probability to the Eagles.

Final

Arizona Cardinals 35
Philadelphia Eagles 31

December 31, 2023 · Lincoln Financial Field · Closing line: Eagles −12

Luck index +47 Cardinals lucky · −47 Eagles

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 5, Eagles win 5.

  1. 1 ARI 26 PHI 7
  2. 2 ARI 24 PHI 13
  3. 3 ARI 24 PHI 16
  4. 4 ARI 17 PHI 13
  5. 5 ARI 16 PHI 14
  6. 6 ARI 17 PHI 19
  7. 7 ARI 16 PHI 20
  8. 8 ARI 7 PHI 14
  9. 9 ARI 16 PHI 27
  10. 10 ARI 10 PHI 28

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.

An off day for the Eagles

Their defense played far below its usual level. In a fresh game against the Cardinals they would win 80% of the time; with this day’s form, 47%.

33 points apart for the Eagles: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Cardinals offenseEPA per play gained +0.41 −0.00 better by 0.41
Cardinals defenseEPA per play allowed +0.24 +0.14 worse by 0.10
Eagles offenseEPA per play gained +0.24 +0.19 better by 0.05
Eagles defenseEPA per play allowed +0.41 +0.07 worse by 0.34

EPA (expected points added) per play on competitive snaps, turnovers left out because they are valued as luck. Usual level: the team’s earlier games this season plus half of last season, pulled toward the league average. One team’s defense and the other team’s offense are the same snaps, so one game can’t fully say whose day it was; it shows how far this one was from both teams’ norms.

How 4,000 replays ended

Cardinals win 53% of them, Eagles 47%, counting the 8% still level after regulation as half each. The line is what actually happened: Cardinals by 4.

Show as a table
Final margin in the replaysShare of replays
Cardinals by 17+9.2%
Cardinals by 9–1613.8%
Cardinals by 1–824.8%
Level after regulation8.1%
Eagles by 1–824.4%
Eagles by 9–1613.2%
Eagles by 17+6.7%

Where the luck was

Take the luck out

The final margin was Cardinals by 4. Remove the luck, one kind at a time, and it becomes Eagles by 2.6.

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.

  • M. Prater, 28 yds made · 97% expected
  • M. Prater, 34 yds made · 93% expected
  • J. Elliott, 43 yds made · 83% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Eagles’ chance of winning

As low as 0% and as high as 92%. 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 Eagles were ahead in it, below while the Cardinals were.
#WhenWhat happenedWin probability forNext drive
1 Q1 10:48 The Cardinals converted 3rd & 43rd & 4th downs · 49% expected +9% ARI ARI: Field goal
2 Q2 12:01 The Cardinals were stopped on 3rd & 73rd & 4th downs · 37% expectedThe Cardinals threw an interception-worthy pass, and it was pickedInterceptions · 48% expected to stay out of the defense's handsReturn touchdown by the EaglesSpecial teams +61% PHI ARI: Field goal
3 Q3 7:21 The Eagles were stopped on 3rd & 53rd & 4th downs · 48% expectedD. Smith dropped a catchable passDrops · 5 drops on 211 catchable balls before this +9% ARI PHI: Punt
4 Q3 2:01 The Cardinals’ two-point try was good3rd & 4th downs · 47% expectedDefensive Holding on the Eagles (Avonte Maddox), 5 yardsJudgment calls · 8 flags in 2689 snaps before, position avg 1 per 216 +15% ARI ARI: Touchdown
5 Q4 10:02 The Eagles converted 3rd & 43rd & 4th downs · 44% expectedNeutral Zone Infraction on the Cardinals (Naquan Jones), 5 yardsPre-snap flags · 2 flags in 775 snaps before, position avg 1 per 316 +17% PHI PHI: Touchdown
6 Q4 5:30 The Cardinals converted 4th & 43rd & 4th downs · 40% expected +16% ARI ARI: Touchdown
7 Q4 2:37 J. Elliott made 43-yard field goalKicks · 83% expected for him +15% PHI PHI: Turnover
8 Q4 0:07 The Eagles threw an interception-worthy pass, and it was pickedInterceptions · 47% expected to stay out of the defense's hands +32% ARI –

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.

  • Darius Slay (PHI CB), out · 1.1 pts
  • Bradley Roby (PHI CB), out · 0.3 pts
  • Zach Cunningham (PHI LB), out · 0.3 pts
  • Marquise Brown (ARI WR), out (IR) · 0.9 pts
  • Dennis Daley (ARI T), out · 0.5 pts
  • Jonathan Ledbetter (ARI DE), out (IR) · 0.4 pts
  • Kyzir White (ARI LB), out (IR) · 0.4 pts
  • Carter O'Donnell (ARI T), out · 0.4 pts
  • Josh Woods (ARI LB), 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

Cardinals 22% · Eagles 78%

Final margin
Cardinals by 4
Luck in points
6.6 for the Cardinals
Luck-adjusted margin
Eagles by 2.6
Replay with same day's form
Cardinals 53% · Eagles 47% 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 · Cardinals · Eagles

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