luckadjusted

Week 2 2020 · September 20, 2020

No FTN charting for this game (drops and interception-worthy throws are not modelled).

Chiefs at Chargers, Week 2 2020: who deserved to win?

The Chiefs beat the Chargers 23–20, but it was a coin flip: replayed with the way both teams played, the Chiefs win 4 of 10. Luck ran their way: 3rd & 4th downs alone were worth 2.2 points to the Chiefs.

The Chiefs won on an off day: they played far below what the matchup promised. In a fresh game against the Chargers they would win 72% of the time; with this day’s form, 40%. The numbers

Before kickoff the Chiefs were 74% favorites. The biggest swing (Q4, 1:14 left): Offensive Holding on the Chiefs, 10 yards, wiping out the play, worth 54 points of win probability to the Chargers.

Final (OT)

Kansas City Chiefs 23
Los Angeles Chargers 20

September 20, 2020 · SoFi Stadium · Closing line: Chiefs −8.5

Luck index +60 Chiefs lucky · −60 Chargers

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 4, Chargers win 6.

  1. 1 KC 44 LAC 25
  2. 2 KC 30 LAC 20
  3. 3 KC 23 LAC 17
  4. 4 KC 35 LAC 33
  5. 5 KC 24 LAC 26
  6. 6 KC 20 LAC 24
  7. 7 KC 24 LAC 33
  8. 8 KC 21 LAC 33
  9. 9 KC 17 LAC 34
  10. 10 KC 21 LAC 47

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.

The Chiefs won on an off day

They played far below what the matchup promised. In a fresh game against the Chargers they would win 72% of the time; with this day’s form, 40%.

32 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 +0.21 worse by 0.09
Chiefs defenseEPA per play allowed +0.09 +0.11 better by 0.03
Chargers offenseEPA per play gained +0.09 +0.11 worse by 0.03
Chargers defenseEPA per play allowed +0.12 +0.11 worse by 0.01

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 40% of them, Chargers 60%, counting the 3% still level after regulation as half each. The line is what actually happened: Chiefs by 3.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+7.1%
Chiefs by 9–1612.3%
Chiefs by 1–820.0%
Level after regulation2.6%
Chargers by 1–826.5%
Chargers by 9–1616.2%
Chargers by 17+15.3%

Where the luck was

Take the luck out

The final margin was Chiefs by 3. Remove the luck, one kind at a time, and it becomes Chiefs by 7.9.

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. Badgley, 41 yds made · 87% expected
  • H. Butker, 58 yds made · 62% expected
  • M. Badgley, 23 yds made · 99% expected
  • H. Butker, 30 yds made · 97% expected
  • H. Butker, 58 yds made · 63% expected
  • Extra point missed · 80% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Chargers’ chance of winning

As low as 0% and as high as 91%. 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 Q4 2:31 M. Badgley made 23-yard field goalKicks · 99% expected for him +16% LAC LAC: Punt
2 Q4 1:19 The Chiefs converted 3rd & 73rd & 4th downs · 37% expected +12% KC KC: Field goal
3 Q4 1:14 Offensive Holding on the Chiefs, 10 yards, wiping out the playJudgment calls +54% LAC LAC: Punt
4 Q4 0:54 The Chiefs converted 3rd & 203rd & 4th downs · 20% expected +22% KC KC: Field goal
5 Q4 0:25 Offensive Holding on the Chiefs, 10 yardsJudgment calls +29% LAC LAC: Punt
6 QOT 4:15 The Chiefs were stopped on 3rd & 43rd & 4th downs · 49% expected +14% LAC KC: Field goal
7 QOT 4:06 The Chiefs converted 4th & 13rd & 4th downs · 76% expected +21% KC KC: Field goal
8 QOT 2:00 H. Butker made 58-yard field goalKicks · 63% expected for him, 7 of 10 from 45+ beforeFalse Start on the Chiefs, 5 yardsPre-snap flags +47% KC –

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.

  • Derwin James (LAC FS), out (IR) · 0.7 pts
  • Drue Tranquill (LAC LB), out (IR) · 0.2 pts
  • Charvarius Ward (KC CB), out · 0.6 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 90% · Chargers 10%

Final margin
Chiefs by 3
Luck in points
4.9 for the Chargers
Luck-adjusted margin
Chiefs by 7.9
Replay with same day's form
Chiefs 40% · Chargers 60% 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 (not available for this game); injuries from snap counts and injury reports. No FTN charting for this game (drops and interception-worthy throws are not modelled).

Methodology and validation · All Week 2 2020 games · Chiefs · Chargers

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