luckadjusted

Week 14 2023 · December 10, 2023

Seahawks at 49ers, Week 14 2023: who deserved to win?

The 49ers beat the Seahawks 28–16, and it was no fluke: replayed with the way both teams actually played, the 49ers win 10 of 10.

Before kickoff the 49ers were 86% favorites. The biggest swing (Q2, 8:26 left): the 49ers converted 3rd & 11, worth 22 points of win probability to the 49ers.

Final

Seattle Seahawks 16
San Francisco 49ers 28

December 10, 2023 · Levi's Stadium · Closing line: 49ers −14.5

Luck index +3 49ers about even · −3 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 0, 49ers win 10.

  1. 1 SEA 30 SF 33
  2. 2 SEA 27 SF 34
  3. 3 SEA 23 SF 34
  4. 4 SEA 27 SF 41
  5. 5 SEA 30 SF 47
  6. 6 SEA 27 SF 48
  7. 7 SEA 26 SF 51
  8. 8 SEA 10 SF 40
  9. 9 SEA 6 SF 41
  10. 10 SEA 6 SF 51

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 3% of them, 49ers 97%, counting the 1% still level after regulation as half each. The line is what actually happened: 49ers by 12.

Show as a table
Final margin in the replaysShare of replays
Seahawks by 17+0.1%
Seahawks by 9–160.4%
Seahawks by 1–81.7%
Level after regulation0.5%
49ers by 1–86.4%
49ers by 9–1613.1%
49ers by 17+77.7%

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.

Swings add up across a game, so in one that went back and forth they can pass 100%. On the scoreboard the same luck was worth +3.4 points to the 49ers: the final margin was 49ers by 12, without the luck 49ers by 8.6. Luck shares are the fitted ones (how much of each kind is luck).

Penalties: Seahawks 5 for 39 yards, 49ers 5 for 30 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

WhenFlagWin probability for
Q1 12:13 Defensive Offside on the 49ers (Nick Bosa), 5 yards, wiping out the play · pre-snap +1% SF 0.0 pts
Q1 1:13 False Start on the Seahawks, 5 yards · pre-snap +1% SF 0.0 pts
Q2 12:52 Illegal Contact on the 49ers (Deommodore Lenoir), 5 yards +4% SEA +1.4 pts
Q2 5:23 Delay of Game on the Seahawks, 5 yards · pre-snap +3% SF +0.8 pts
Q2 3:07 False Start on the 49ers, 5 yards · pre-snap +1% SEA +0.5 pts
Q2 1:03 Illegal Forward Pass on the Seahawks (Drew Lock), 4 yards +1% SF +0.3 pts
Q3 13:13 Offensive Holding on the 49ers, 10 yards, wiping out the play +5% SEA +1.4 pts
Q4 13:04 Offensive Holding on the Seahawks, 10 yards +1% SF +0.9 pts
Q4 11:49 Unnecessary Roughness on the Seahawks (Jaxon Smith-Njigba), 15 yards +2% SF +1.6 pts
Q4 5:25 Defensive Offside on the 49ers (Nick Bosa), 5 yards, wiping out the play · pre-snap +7% SEA +6.6 pts

Seahawks penalties, every game · 49ers penalties, every game · All teams, 2023

When it happened

49ers’ chance of winning

As low as 32% 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 49ers were ahead in it, below while the Seahawks were.
#WhenWhat happenedWin probability forNext drive
1 Q1 10:24 The Seahawks converted 3rd & 63rd & 4th downs · 35% expected +6% SEA SEA: Touchdown
2 Q1 2:01 K. Walker dropped a catchable passDrops · 2 drops on 48 catchable balls before this +5% SF SEA: Field goal
3 Q2 14:24 The 49ers were intercepted on a well-placed throwInterceptions · 0% expected to stay out of the defense's hands +12% SEA SF: Touchdown
4 Q2 8:26 The 49ers converted 3rd & 113rd & 4th downs · 29% expected +22% SF SF: Touchdown
5 Q3 14:51 The Seahawks got away with an interception-worthy throwInterceptions · 49% expected to stay out of the defense's hands +7% SEA SEA: Punt
6 Q3 11:16 The 49ers were stopped on 3rd & 63rd & 4th downs · 40% expected +6% SEA SF: Punt
7 Q3 8:42 The Seahawks converted 3rd & 83rd & 4th downs · 29% expected +7% SEA SEA: Punt
8 Q4 5:25 Defensive Offside on the 49ers (Nick Bosa), 5 yards, wiping out the playPre-snap flags · 11 flags in 3526 snaps before, position avg 1 per 295 +7% SEA 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.

  • Talanoa Hufanga (SF SS), out (IR) · 0.6 pts
  • Spencer Burford (SF G), out · 0.3 pts
  • Arik Armstead (SF DT), out · 0.3 pts
  • Geno Smith (SEA QB), out, replaced by d.lock · 3.7 pts
  • Tre Brown (SEA CB), out · 0.3 pts
  • Phil Haynes (SEA G), out (IR) · 0.2 pts
  • Uchenna Nwosu (SEA LB), 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 0% · 49ers 100%

Final margin
49ers by 12
Luck in points
3.4 for the 49ers
Luck-adjusted margin
49ers by 8.6
Replay with same day's form
Seahawks 3% · 49ers 97% 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; injuries from snap counts and injury reports.

Methodology and validation · All Week 14 2023 games · Seahawks · 49ers

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