Week 1 2021 · September 12, 2021
No FTN charting for this game (drops and interception-worthy throws are not modelled).
Browns at Chiefs, Week 1 2021: who deserved to win?
The Chiefs beat the Browns 33–29 and were the better team on the day: replayed with the same form, they win 7 of 10. The Browns had the bounces: judgment calls alone were worth 3.4 points to the Browns.
Before kickoff the Chiefs were 66% favorites. The biggest swing (Q4, 7:08 left): the Chiefs converted 3rd & 3, worth 11 points of win probability to the Chiefs.
Final
 Cleveland Browns | 29 |
|---|---|
 Kansas City Chiefs | 33 |
Replay with same day's form
Luck index +30 Chiefs lucky · −30 Browns
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. Browns win 3, Chiefs win 7.
- 1 CLE 30 KC 13
- 2 CLE 21 KC 14
- 3 CLE 20 KC 17
- 4 CLE 17 KC 20
- 5 CLE 27 KC 31
- 6 CLE 27 KC 34
- 7 CLE 24 KC 34
- 8 CLE 20 KC 34
- 9 CLE 24 KC 41
- 10 CLE 23 KC 48
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
Browns win 30% of them, Chiefs 70%, counting the 5% still level after regulation as half each. The line is what actually happened: Chiefs by 4.
Show as a table
| Final margin in the replays | Share of replays |
|---|---|
| Browns by 17+ | 3.5% |
| Browns by 9–16 | 7.2% |
| Browns by 1–8 | 15.5% |
| Level after regulation | 4.8% |
| Chiefs by 1–8 | 25.5% |
| Chiefs by 9–16 | 21.3% |
| Chiefs by 17+ | 22.1% |
Where the luck was
Take the luck out
The final margin was Chiefs by 4. Remove the luck, one kind at a time, and it becomes Chiefs by 8.7.
The kicks
How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.
- H. Butker, 28 yds made · 98% expected
- H. Butker, 43 yds made · 83% expected
When it happened
Chiefs’ chance of winning
As low as 13% and as high as 100%. Numbers mark the biggest luck moments, listed below.
| # | When | What happened | Win probability for | Next drive |
|---|---|---|---|---|
| 1 | Q1 11:35 | The Browns converted 3rd & 33rd & 4th downs · 55% expected | +6% CLE | CLE: Touchdown |
| 2 | Q1 9:18 | The Browns converted 4th & 33rd & 4th downs · 54% expected | +9% CLE | CLE: Touchdown |
| 3 | Q1 7:53 | The Browns’ two-point try was good3rd & 4th downs · 47% expectedEncroachment on the Chiefs (Chris Jones), 1 yardsPre-snap flags · 17 flags in 1658 snaps before, position avg 1 per 273 | +7% CLE | CLE: Touchdown |
| 4 | Q3 2:44 | The Chiefs converted 3rd & 23rd & 4th downs · 65% expected | +9% KC | KC: Field goal |
| 5 | Q4 8:50 | The Browns were stopped on 3rd & 123rd & 4th downs · 27% expected | +6% KC | CLE: Turnover on downs |
| 6 | Q4 7:08 | The Chiefs converted 3rd & 33rd & 4th downs · 48% expected | +11% KC | KC: Touchdown |
| 7 | Q4 5:34 | The Browns were stopped on 3rd & 73rd & 4th downs · 37% expected | +7% KC | CLE: Punt |
| 8 | Q4 3:41 | The Chiefs were stopped on 3rd & 103rd & 4th downs · 32% expected | +7% CLE | KC: Punt |
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.
- Frank Clark (KC DE), out · 0.8 pts
- Tyrann Mathieu (KC SS), out · 0.8 pts
- Tyrann Mathieu (KC S), out · 0.8 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
Browns 9% · Chiefs 91%
- Final margin
- Chiefs by 4
- Luck in points
- 4.7 for the Browns
- Luck-adjusted margin
- Chiefs by 8.7
- Replay with same day's form
- Browns 30% · Chiefs 70% 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 1 2021 games · 
Browns · 
Chiefs
More from Week 1 2021
- Cowboys at Buccaneers TB 31–29 · replay 74% for the winner
- Cardinals at Titans ARI 38–13 · replay 78% for the winner
- Jaguars at Texans HOU 37–21 · replay 83% for the winner
- Chargers at Washington LAC 20–16 · replay 89% for the winner
- Vikings at Bengals CIN 27–24 · replay 80% for the winner
- Jets at Panthers CAR 19–14 · replay 93% for the winner
- Eagles at Falcons PHI 32–6 · replay 69% for the winner
- Steelers at Bills PIT 23–16 · replay 56% for the winner
- Seahawks at Colts SEA 28–16 · replay 62% for the winner
- 49ers at Lions SF 41–33 · replay 57% for the winner
- Broncos at Giants DEN 27–13 · replay 73% for the winner
- Packers vs Saints NO 38–3 · replay 77% for the winner
- Dolphins at Patriots MIA 17–16 · replay 78% for the winner
- Bears at Rams LA 34–14 · replay 91% for the winner
- Ravens at Raiders LV 33–27 · replay 72% for the winner