luckadjusted

Week 2 2021 · September 19, 2021

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

Chiefs at Ravens, Week 2 2021: who deserved to win?

The Ravens beat the Chiefs 36–35 and were the better team on the day: replayed with the same form, they win 7 of 10. The Chiefs had the bounces: injuries alone were worth 2.6 points to the Chiefs.

Before kickoff the Chiefs were 60% favorites. The biggest swing (Q1, 14:19 left): the Ravens were stopped on 3rd & 8, worth 35 points of win probability to the Chiefs.

Final

Kansas City Chiefs 35
Baltimore Ravens 36

September 19, 2021 · M&T Bank Stadium · Closing line: Chiefs −3.5

Luck index +33 Ravens lucky · −33 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 3, Ravens win 7.

  1. 1 KC 38 BAL 21
  2. 2 KC 41 BAL 34
  3. 3 KC 24 BAL 21
  4. 4 KC 42 BAL 45
  5. 5 KC 23 BAL 28
  6. 6 KC 26 BAL 34
  7. 7 KC 31 BAL 43
  8. 8 KC 14 BAL 30
  9. 9 KC 24 BAL 44
  10. 10 KC 20 BAL 49

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 33% of them, Ravens 67%, counting the 4% still level after regulation as half each. The line is what actually happened: Ravens by 1.

Show as a table
Final margin in the replaysShare of replays
Chiefs by 17+5.5%
Chiefs by 9–168.5%
Chiefs by 1–815.9%
Level after regulation3.5%
Ravens by 1–824.4%
Ravens by 9–1618.9%
Ravens by 17+23.3%

Where the luck was

Take the luck out

The final margin was Ravens by 1. Remove the luck, one kind at a time, and it becomes Chiefs by 1.4.

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).

When it happened

Ravens’ chance of winning

As low as 8% and as high as 100%. 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 Ravens were ahead in it, below while the Chiefs were.
#WhenWhat happenedWin probability forNext drive
1 Q1 14:19 The Ravens were stopped on 3rd & 83rd & 4th downs · 36% expectedReturn touchdown by the ChiefsSpecial teams +35% KC BAL: Touchdown
2 Q1 6:54 The Chiefs converted 3rd & 23rd & 4th downs · 65% expected +8% KC KC: Touchdown
3 Q3 9:39 The Ravens converted 3rd & 43rd & 4th downs · 50% expected +14% BAL BAL: Touchdown
4 Q3 4:22 The Ravens were stopped on 3rd & 83rd & 4th downs · 36% expected +7% KC BAL: Punt
5 Q4 5:31 The Ravens converted 3rd & 53rd & 4th downs · 45% expected +8% BAL BAL: Touchdown
6 Q4 3:18 The Ravens converted 3rd & 13rd & 4th downs · 71% expected +7% BAL BAL: Touchdown
7 Q4 1:26 The Chiefs fumbled and the Ravens recoveredFumble bounces · loose balls are close to 50/50 +26% BAL –
8 Q4 1:05 The Ravens converted 4th & 13rd & 4th downs · 77% expected +8% BAL BAL: End of game

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.

  • Marcus Peters (BAL CB), out (IR) · 1.5 pts
  • Derek Wolfe (BAL DE), out · 0.6 pts
  • Miles Boykin (BAL WR), out (IR) · 0.3 pts
  • J.K. Dobbins (BAL RB), 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 80% · Ravens 20%

Final margin
Ravens by 1
Luck in points
2.4 for the Ravens
Luck-adjusted margin
Chiefs by 1.4
Replay with same day's form
Chiefs 33% · Ravens 67% 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 2021 games · Chiefs · Ravens

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