luckadjusted

Week 15 2021 · December 21, 2021

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

Seahawks at Rams, Week 15 2021: who deserved to win?

The Rams beat the Seahawks 20–10, and it was no fluke: replayed with the way both teams actually played, the Rams win 9 of 10.

Before kickoff the Rams were 71% favorites. The biggest swing (Q2, 3:40 left): the Rams converted 3rd & 17, worth 11 points of win probability to the Rams.

Final

Seattle Seahawks 10
Los Angeles Rams 20

December 21, 2021 · SoFi Stadium · Closing line: Rams −7.5

Luck index +11 Rams about even · −11 Seahawks

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. Seahawks win 1, Rams win 9.

  1. 1 SEA 27 LA 20
  2. 2 SEA 17 LA 20
  3. 3 SEA 16 LA 22
  4. 4 SEA 30 LA 38
  5. 5 SEA 12 LA 23
  6. 6 SEA 14 LA 29
  7. 7 SEA 16 LA 34
  8. 8 SEA 13 LA 34
  9. 9 SEA 13 LA 38
  10. 10 SEA 14 LA 45

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

Seahawks win 11% of them, Rams 89%, counting the 2% still level after regulation as half each. The line is what actually happened: Rams by 10.

Show as a table
Final margin in the replaysShare of replays
Seahawks by 17+0.8%
Seahawks by 9–162.7%
Seahawks by 1–86.3%
Level after regulation1.7%
Rams by 1–817.3%
Rams by 9–1620.1%
Rams by 17+51.2%

Where the luck was

Take the luck out

The final margin was Rams by 10. Remove the luck, one kind at a time, and it becomes Rams by 2.9.

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. Gay, 55 yds made · 68% expected
  • J. Myers, 39 yds made · 90% expected
  • M. Gay, 35 yds made · 94% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Rams’ chance of winning

As low as 28% 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 Rams were ahead in it, below while the Seahawks were.
#WhenWhat happenedWin probability forNext drive
1 Q1 9:34 Illegal Formation on the Rams, 5 yards, wiping out the playPre-snap flags +8% SEA SEA: Punt
2 Q1 3:14 The Rams converted 3rd & 123rd & 4th downs · 21% expected +8% LA LA: Turnover
3 Q2 3:40 The Rams converted 3rd & 173rd & 4th downs · 17% expected +11% LA LA: Turnover on downs
4 Q3 13:58 Offensive Holding on the Seahawks, 10 yards, wiping out the playJudgment calls +7% LA LA: Touchdown
5 Q3 10:27 The Seahawks converted 3rd & 93rd & 4th downs · 27% expected +7% SEA SEA: Touchdown
6 Q4 6:18 The Rams were stopped on 3rd & 73rd & 4th downs · 31% expected +10% SEA LA: Punt
7 Q4 4:12 The Seahawks were stopped on 3rd & 53rd & 4th downs · 38% expectedFalse Start on the Seahawks (Rashaad Penny), 4 yardsPre-snap flags · 0 flags in 306 snaps before, position avg 1 per 773 +9% LA SEA: Turnover on downs
8 Q4 3:27 The Seahawks were stopped on 4th & 63rd & 4th downs · 34% expectedUnsportsmanlike Conduct on the Seahawks (DeeJay Dallas), 15 yardsJudgment calls · 0 flags in 625 snaps before, position avg 1 per 773 +7% LA SEA: Turnover

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.

  • Rob Havenstein (LA T), out (IR) · 1.0 pts
  • Robert Woods (LA WR), out (IR) · 0.9 pts
  • Tyler Higbee (LA TE), out (IR) · 0.9 pts
  • Jordan Fuller (LA SS), out (IR) · 0.4 pts
  • Terrell Lewis (LA LB), out · 0.1 pts
  • Tyler Lockett (SEA WR), out (IR) · 1.1 pts
  • Brandon Shell (SEA T), out (IR) · 0.7 pts
  • Jamal Adams (SEA SS), out (IR) · 0.7 pts
  • D.J. Reed (SEA CB), out (IR) · 0.6 pts
  • Tre Brown (SEA DB), out (IR) · 0.2 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

Seahawks 30% · Rams 70%

Final margin
Rams by 10
Luck in points
7.1 for the Rams
Luck-adjusted margin
Rams by 2.9
Replay with same day's form
Seahawks 11% · Rams 89% 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 15 2021 games · Seahawks · Rams

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