luckadjusted

Week 2 2023 · September 17, 2023

Chiefs at Jaguars, Week 2 2023: who deserved to win?

The Chiefs beat the Jaguars 17–9, but it was a coin flip: replayed with the way both teams played, the Chiefs win 5 of 10. Luck ran their way: 3rd & 4th downs alone were worth 15 points of win probability to the Chiefs.

Before kickoff the Chiefs were 60% favorites. The biggest swing (Q2, 11:07 left): the Chiefs were stopped on 3rd & 7, worth 16 points of win probability to the Jaguars.

Final

Kansas City Chiefs 17
Jacksonville Jaguars 9

September 17, 2023 · TIAA Bank Stadium · Closing line: Chiefs −3.5

Luck index +45 Chiefs lucky · −45 Jaguars

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. Chiefs win 5, Jaguars win 5.

  1. 1 KC 29 JAX 6
  2. 2 KC 24 JAX 7
  3. 3 KC 28 JAX 17
  4. 4 KC 20 JAX 14
  5. 5 KC 20 JAX 17
  6. 6 KC 15 JAX 17
  7. 7 KC 26 JAX 31
  8. 8 KC 14 JAX 23
  9. 9 KC 10 JAX 23
  10. 10 KC 13 JAX 36

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

Chiefs win 55% of them, Jaguars 45%, counting the 6% still level after regulation as half each. The line is what actually happened: Chiefs by 8.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+13.3%
Chiefs by 9–1615.0%
Chiefs by 1–821.1%
Level after regulation6.2%
Jaguars by 1–821.8%
Jaguars by 9–1613.3%
Jaguars by 17+9.3%

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 +4.4 points to the Jaguars: the final margin was Chiefs by 8, without the luck Chiefs by 12.4. 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.

  • B. McManus, 32 yds made · 95% expected
  • B. McManus, 49 yds made · 75% expected
  • B. McManus, 22 yds made · 100% expected
  • H. Butker, 38 yds made · 90% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Chiefs 12 for 94 yards, Jaguars 2 for 10 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 toward luck, pre-snap fouls mostly don’t. How calls are valued

WhenFlagWin probability for
Q1 9:01 Defensive Too Many Men on Field on the Chiefs, 5 yards · pre-snap +3% JAX +0.6 pts
Q1 5:32 Offensive Holding on the Chiefs, 10 yards, wiping out the play +11% JAX +2.7 pts
Q1 2:08 Defensive Pass Interference on the Chiefs (L'Jarius Sneed), 11 yards +6% JAX +1.8 pts
Q2 14:14 False Start on the Jaguars (Travis Etienne), 5 yards · pre-snap +2% KC +0.9 pts
Q2 11:07 Unsportsmanlike Conduct on the Chiefs (Travis Kelce), 15 yards +3% JAX +1.1 pts
Q2 10:12 False Start on the Chiefs, 5 yards · pre-snap +2% JAX +0.6 pts
Q2 8:37 Neutral Zone Infraction on the Chiefs (Derrick Nnadi), 5 yards · pre-snap +1% JAX +0.8 pts
Q2 3:09 Illegal Formation on the Chiefs, 5 yards, wiping out the play · pre-snap +4% JAX +0.9 pts
Q3 7:11 Offensive Holding on the Chiefs, 10 yards +3% JAX +0.9 pts
Q3 6:46 Offensive Holding on the Chiefs, 8 yards, wiping out the play +6% JAX +1.9 pts
Q3 3:56 Delay of Game on the Jaguars, 5 yards · pre-snap +1% KC +0.8 pts
Q4 14:53 Defensive Pass Interference on the Chiefs (Justin Reid), 10 yards +10% JAX +3.3 pts
Q4 8:25 False Start on the Chiefs, 5 yards · pre-snap +1% JAX +0.6 pts
Q4 8:25 False Start on the Chiefs, 5 yards · pre-snap +1% JAX +0.5 pts

Chiefs penalties, every game · Jaguars penalties, every game · All teams, 2023

When it happened

Jaguars’ chance of winning

As low as 0% and as high as 71%. 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 Jaguars were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q1 5:32 Offensive Holding on the Chiefs, 10 yards, wiping out the playJudgment calls +11% JAX JAX: Punt
2 Q2 15:00 The Chiefs fumbled and the Jaguars recoveredFumble bounces · loose balls are close to 50/50 +7% JAX KC: Turnover
3 Q2 11:07 The Chiefs were stopped on 3rd & 73rd & 4th downs · 35% expectedThe Chiefs fumbled and the Jaguars recoveredFumble bounces · loose balls are close to 50/50Unsportsmanlike Conduct on the Chiefs (Travis Kelce), 15 yardsJudgment calls · 22 flags in 4411 snaps before, position avg 1 per 286 +16% JAX KC: Turnover
4 Q2 4:10 The Jaguars were stopped on 4th & 53rd & 4th downs · 37% expected +8% KC JAX: Field goal
5 Q2 2:00 The Chiefs converted 4th & 23rd & 4th downs · 60% expected +8% KC KC: Touchdown
6 Q3 13:35 The Chiefs converted 3rd & 103rd & 4th downs · 28% expected +11% KC KC: Touchdown
7 Q3 11:36 The Chiefs converted 3rd & 33rd & 4th downs · 44% expected +8% KC KC: Touchdown
8 Q4 14:53 Defensive Pass Interference on the Chiefs (Justin Reid), 10 yardsJudgment calls · 4 flags in 4381 snaps before, position avg 1 per 462 +10% JAX JAX: Field goal

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.

  • Cam Robinson (JAX T), out (IR) · 0.8 pts
  • Dawuane Smoot (JAX DE), 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

Chiefs 96% · Jaguars 4%

Final margin
Chiefs by 8
Luck in points
4.4 for the Jaguars
Luck-adjusted margin
Chiefs by 12.4
Replay with same day's form
Chiefs 55% · Jaguars 45% 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 2 2023 games · Chiefs · Jaguars

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