Week 15 2021 · December 16, 2021
No FTN charting for this game (drops and interception-worthy throws are not modelled).
Chiefs at Chargers, Week 15 2021: who deserved to win?
The Chiefs beat the Chargers 34–28 and were the better team on the day: replayed with the same form, they win 7 of 10.
Before kickoff the Chiefs were 59% favorites. The biggest swing (Q4, 11:02 left): the Chargers were stopped on 3rd & 1, worth 35 points of win probability to the Chiefs.
Final (OT)
 Kansas City Chiefs | 34 |
|---|---|
 Los Angeles Chargers | 28 |
Replay with same day's form
Luck index +27 Chiefs lucky · −27 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 7, Chargers win 3.
- 1 KC 51 LAC 20
- 2 KC 34 LAC 14
- 3 KC 38 LAC 23
- 4 KC 48 LAC 36
- 5 KC 40 LAC 31
- 6 KC 21 LAC 16
- 7 KC 33 LAC 30
- 8 KC 31 LAC 34
- 9 KC 30 LAC 37
- 10 KC 32 LAC 49
Three other ways to ask
Each answers a different question, so none of them replaces the replay above.
Before kickoff
The closing betting line, turned into a probability. What everyone knew before the game.
Same teams, fresh 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.
Only coin-flips re-rolled
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 73% of them, Chargers 27%, counting the 5% still level after regulation as half each. The line is what actually happened: Chiefs by 6.
Show as a table
| Final margin in the replays | Share of replays |
|---|---|
| Chiefs by 17+ | 26.8% |
| Chiefs by 9–16 | 19.8% |
| Chiefs by 1–8 | 23.9% |
| Level after regulation | 4.6% |
| Chargers by 1–8 | 14.6% |
| Chargers by 9–16 | 7.1% |
| Chargers by 17+ | 3.2% |
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.
The kicks
How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.
- H. Butker, 30 yds made · 98% expected
- H. Butker, 33 yds made · 96% expected
Penalties: Chiefs 4 for 36 yards, Chargers 5 for 60 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
| When | Flag | Win probability for |
|---|---|---|
| Q1 12:55 | Offensive Holding on the Chiefs, 8 yards | +2% LAC +1.0 pts |
| Q1 4:06 | Defensive Too Many Men on Field on the Chargers, 5 yards · pre-snap | +1% KC +0.6 pts |
| Q1 3:08 | Illegal Use of Hands on the Chargers (Jerry Tillery), 5 yards | +2% KC +0.6 pts |
| Q2 9:12 | Offensive Holding on the Chiefs (Darrel Williams), 8 yards | +2% LAC +0.8 pts |
| Q3 15:00 | Defensive Pass Interference on the Chargers, 30 yards | +4% KC +2.0 pts |
| Q3 10:14 | Neutral Zone Infraction on the Chiefs (Frank Clark), 5 yards · pre-snap | +3% LAC +1.0 pts |
| Q4 13:47 | Defensive Pass Interference on the Chiefs (Anthony Hitchens), 15 yards | +3% LAC +0.9 pts |
| Q4 7:44 | Roughing the Passer on the Chargers (Joey Bosa), 15 yards | +10% KC +0.5 pts |
| Q4 0:39 | Illegal Shift on the Chargers, 5 yards · pre-snap | +3% KC +0.5 pts |
Chiefs penalties, every game · Chargers penalties, every game · All teams, 2021
When it happened
Chargers’ chance of winning
As low as 0% and as high as 91%. Numbers mark the biggest luck moments, listed below.
| # | When | What happened | Win probability for | Next drive |
|---|---|---|---|---|
| 1 | Q2 0:03 | The Chargers were stopped on 4th & 13rd & 4th downs · 68% expected | +10% KC | LAC: Turnover on downs |
| 2 | Q3 6:24 | The Chiefs converted 3rd & 103rd & 4th downs · 33% expected | +17% KC | KC: Turnover on downs |
| 3 | Q3 1:50 | The Chiefs were stopped on 4th & 13rd & 4th downs · 72% expected | +19% LAC | KC: Turnover |
| 4 | Q4 11:02 | The Chargers were stopped on 3rd & 13rd & 4th downs · 69% expectedThe Chargers fumbled and the Chiefs recoveredFumble bounces · loose balls are close to 50/50 | +35% KC | LAC: Touchdown |
| 5 | Q4 9:39 | The Chiefs were stopped on 3rd & 33rd & 4th downs · 58% expected | +21% LAC | KC: Touchdown |
| 6 | Q4 8:55 | The Chiefs converted 3rd & 53rd & 4th downs · 47% expected | +17% KC | KC: Touchdown |
| 7 | Q4 7:44 | The Chiefs’ two-point try was good3rd & 4th downs · 47% expectedRoughing the Passer on the Chargers (Joey Bosa), 15 yardsJudgment calls · 18 flags in 2067 snaps before, position avg 1 per 409 | +21% KC | KC: Touchdown |
| 8 | Q4 2:24 | The Chargers converted 3rd & 63rd & 4th downs · 32% expected | +14% LAC | LAC: Touchdown |
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
- L'Jarius Sneed (KC CB), out · 0.7 pts
- Chris Jones (KC DT), out (IR) · 0.7 pts
- Mike Remmers (KC T), out (IR) · 0.6 pts
- Andrew Wylie (KC G), out · 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 80% · Chargers 20%
- Final margin
- Chiefs by 6
- Luck in points
- 0.8 for the Chiefs
- Luck-adjusted margin
- Chiefs by 5.2
- Replay with same day's form
- Chiefs 73% · Chargers 27% unchanged: why
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 15 2021 games · 
Chiefs · 
Chargers
More from Week 15 2021
- Patriots at Colts IND 27–17 · replay 75% for the winner
- Cardinals at Lions DET 30–12 · replay 20% for the winner
- Panthers at Bills BUF 31–14 · replay 83% for the winner
- Cowboys at Giants DAL 21–6 · replay 73% for the winner
- Texans at Jaguars HOU 30–16 · replay 31% for the winner
- Jets at Dolphins MIA 31–24 · replay 72% for the winner
- Titans at Steelers PIT 19–13 · replay 67% for the winner
- Falcons at 49ers SF 31–13 · replay 89% for the winner
- Bengals at Broncos CIN 15–10 · replay 67% for the winner
- Packers at Ravens GB 31–30 · replay 77% for the winner
- Saints at Buccaneers NO 9–0 · replay 17% for the winner
- Raiders at Browns LV 16–14 · replay 52% for the winner
- Vikings at Bears MIN 17–9 · replay 44% for the winner
- Seahawks at Rams LA 20–10 · replay 89% for the winner
- Washington at Eagles PHI 27–17 · replay 92% for the winner