luckadjusted

Week 1 2025 · September 5, 2025

Chiefs vs Chargers, Week 1 2025: who deserved to win?

The Chargers beat the Chiefs 27–21, and it was no fluke: replayed with the way both teams actually played, the Chargers win 9 of 10.

An off day for the Chiefs: their defense played far below its usual level. In a fresh game against the Chargers they would win 53% of the time; with this day’s form, 14%. The numbers

Before kickoff the Chiefs were 59% favorites. The biggest swing (Q4, 3:24 left): the Chiefs converted 4th & 7, worth 11 points of win probability to the Chiefs.

Final

Kansas City Chiefs 21
Los Angeles Chargers 27

September 5, 2025 · SoFi Stadium · Closing line: Chiefs −3

Luck index +14 Chargers about even · −14 Chiefs

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 1, Chargers win 9.

  1. 1 KC 23 LAC 17
  2. 2 KC 13 LAC 15
  3. 3 KC 6 LAC 10
  4. 4 KC 10 LAC 17
  5. 5 KC 7 LAC 16
  6. 6 KC 10 LAC 21
  7. 7 KC 10 LAC 23
  8. 8 KC 0 LAC 17
  9. 9 KC 10 LAC 31
  10. 10 KC 13 LAC 41

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 Chiefs

Their defense played far below its usual level. In a fresh game against the Chargers they would win 53% of the time; with this day’s form, 14%.

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

UnitThis gameUsual levelBetter or worse than usual
Chiefs offenseEPA per play gained +0.12 +0.14 worse by 0.01
Chiefs defenseEPA per play allowed +0.32 +0.09 worse by 0.23
Chargers offenseEPA per play gained +0.32 +0.09 better by 0.23
Chargers defenseEPA per play allowed +0.12 +0.07 worse by 0.05

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

Chiefs win 14% of them, Chargers 86%, counting the 1% still level after regulation as half each. The line is what actually happened: Chargers by 6.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+0.5%
Chiefs by 9–163.4%
Chiefs by 1–89.6%
Level after regulation0.9%
Chargers by 1–828.1%
Chargers by 9–1624.4%
Chargers by 17+33.1%

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 +0.8 points to the Chiefs: the final margin was Chargers by 6, without the luck Chargers by 6.8. 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.

  • C. Dicker, 39 yds made · 92% expected
  • H. Butker, 35 yds made · 95% expected
  • C. Dicker, 36 yds made · 95% expected
  • H. Butker, 59 yds made · 65% expected
  • H. Butker, 27 yds made · 99% expected
  • Extra point missed · 95% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Chiefs 10 for 71 yards, Chargers 6 for 49 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 15:00 Offensive Holding on the Chiefs (Joshua Williams), 10 yards +3% LAC +0.7 pts
Q1 9:23 Defensive Offside on the Chiefs (George Karlaftis III), 5 yards · pre-snap +2% LAC +1.4 pts
Q1 9:16 Roughing the Passer on the Chiefs (George Karlaftis III), 8 yards +1% LAC +1.5 pts
Q1 7:19 False Start on the Chiefs, 5 yards · pre-snap +1% LAC +0.6 pts
Q1 3:27 Illegal Bat on the Chargers (Ladd McConkey), 10 yards +2% KC +1.0 pts
Q1 0:42 Offensive Holding on the Chargers (Ladd McConkey), 10 yards, wiping out the play +2% KC +2.0 pts
Q1 0:12 Offensive Holding on the Chargers, 10 yards, wiping out the play +6% KC +2.8 pts
Q2 8:13 Offensive Holding on the Chiefs, 10 yards +5% LAC +1.4 pts
Q2 0:59 Delay of Game on the Chargers, 5 yards · pre-snap 0% KC +0.5 pts
Q2 0:17 False Start on the Chiefs, 5 yards · pre-snap +1% LAC +0.7 pts
Q2 0:17 False Start on the Chiefs, 5 yards · pre-snap +1% LAC +0.5 pts
Q3 13:29 Offensive Holding on the Chiefs, 10 yards +1% LAC +1.0 pts
Q3 10:34 False Start on the Chiefs, 5 yards · pre-snap +1% LAC +0.9 pts
Q3 8:30 Unnecessary Roughness on the Chargers (Teair Tart), 9 yards +3% KC +0.9 pts
Q3 5:18 False Start on the Chargers, 5 yards · pre-snap 0% KC +0.6 pts
Q4 5:09 Face Mask on the Chiefs (Jaden Hicks), 8 yards +2% LAC +0.7 pts

Chiefs penalties, every game · Chargers penalties, every game · All teams, 2025

When it happened

Chargers’ chance of winning

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 Chargers were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q2 8:45 The Chiefs converted 4th & 13rd & 4th downs · 75% expected +6% KC KC: Field goal
2 Q2 0:03 H. Butker made 59-yard field goalKicks · 65% expected for him, 45 of 61 from 45+ before +7% KC KC: Touchdown
3 Q3 10:10 The Chiefs converted 3rd & 83rd & 4th downs · 33% expected +7% KC KC: Touchdown
4 Q3 8:05 The Chiefs missed an extra pointKicks · extra points are made about 94% of the time +7% LAC KC: Touchdown
5 Q3 5:46 The Chargers converted 4th & 13rd & 4th downs · 74% expected +6% LAC LAC: Touchdown
6 Q3 0:36 The Chargers converted 3rd & 33rd & 4th downs · 53% expected +8% LAC LAC: Touchdown
7 Q4 12:04 The Chiefs’ two-point try failed3rd & 4th downs · 47% expected +7% LAC KC: Field goal
8 Q4 3:24 The Chiefs converted 4th & 73rd & 4th downs · 36% expected +11% KC KC: 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.

  • Rashawn Slater (LAC T), out (IR) · 1.0 pts
  • Josh Harris (LAC 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

Chiefs 19% · Chargers 81%

Final margin
Chargers by 6
Luck in points
0.8 for the Chiefs
Luck-adjusted margin
Chargers by 6.8
Replay with same day's form
Chiefs 14% · Chargers 86% 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 1 2025 games · Chiefs · Chargers

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