luckadjusted

Week 4 2025 · September 28, 2025

Jaguars at 49ers, Week 4 2025: who deserved to win?

The Jaguars beat the 49ers 26–21, but the 49ers played well enough to win it: they take 7 of 10 replays with the same day's form. Luck ran their way: drops alone were worth 17 points of win probability to the Jaguars.

Before kickoff the 49ers were 60% favorites. The biggest swing (Q3, 8:18 left): Defensive Pass Interference on the 49ers (Upton Stout), 13 yards, wiping out the play, worth 24 points of win probability to the Jaguars.

Final

Jacksonville Jaguars 26
San Francisco 49ers 21

September 28, 2025 · Levi's Stadium · Closing line: 49ers −3.5

Luck index +68 Jaguars very lucky · −68 49ers

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. Jaguars win 3, 49ers win 7.

  1. 1 JAX 38 SF 21
  2. 2 JAX 34 SF 27
  3. 3 JAX 26 SF 23
  4. 4 JAX 14 SF 16
  5. 5 JAX 30 SF 34
  6. 6 JAX 9 SF 16
  7. 7 JAX 24 SF 34
  8. 8 JAX 20 SF 34
  9. 9 JAX 16 SF 36
  10. 10 JAX 10 SF 38

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

Jaguars win 32% of them, 49ers 68%, counting the 4% still level after regulation as half each. The line is what actually happened: Jaguars by 5.

Show as a table
Final margin in the replaysShare of replays
Jaguars by 17+4.4%
Jaguars by 9–168.2%
Jaguars by 1–815.3%
Level after regulation4.2%
49ers by 1–825.3%
49ers by 9–1620.9%
49ers by 17+21.8%

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 +10.7 points to the Jaguars: the final margin was Jaguars by 5, without the luck 49ers by 5.7. Luck shares are the fitted ones (how much of each kind is luck).

The kicks

How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.

  • E. Pineiro, 26 yds made · 99% expected
  • E. Pineiro, 23 yds made · 99% expected
  • C. Little, 26 yds made · 99% expected
  • C. Little, 44 yds made · 82% expected
  • C. Little, 47 yds missed · 78% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Jaguars 12 for 90 yards, 49ers 5 for 54 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 8:33 Neutral Zone Infraction on the 49ers (Sam Okuayinonu), 5 yards · pre-snap +1% JAX +0.5 pts
Q2 13:10 Unnecessary Roughness on the Jaguars (Maason Smith), 10 yards +3% SF +1.0 pts
Q2 12:27 Offensive Holding on the Jaguars, 8 yards +3% SF +1.4 pts
Q2 12:06 Offensive Holding on the Jaguars, 5 yards +2% SF +0.3 pts
Q2 8:33 Delay of Game on the Jaguars, 5 yards · pre-snap +2% SF +1.3 pts
Q2 2:37 Kick Catch Interference on the Jaguars (Rayuan Lane), 15 yards +2% SF +1.4 pts
Q2 1:30 False Start on the 49ers, 6 yards · pre-snap +1% JAX +0.7 pts
Q2 0:32 Face Mask on the 49ers (Dee Winters), 15 yards +4% JAX +1.9 pts
Q2 0:21 False Start on the Jaguars, 5 yards · pre-snap 0% SF +0.6 pts
Q3 12:55 False Start on the Jaguars, 5 yards · pre-snap +2% SF +0.7 pts
Q3 9:26 Defensive Pass Interference on the Jaguars (Tyson Campbell), 7 yards 0% SF +1.1 pts
Q3 9:23 Defensive Holding on the Jaguars (Dennis Gardeck), 5 yards +2% SF +0.1 pts
Q3 8:18 Defensive Pass Interference on the 49ers (Upton Stout), 13 yards, wiping out the play +26% JAX +5.8 pts
Q3 8:18 False Start on the Jaguars, 5 yards · pre-snap +2% SF +0.9 pts
Q3 5:25 Offensive Holding on the Jaguars (Brenton Strange), 10 yards +7% SF +1.5 pts
Q4 7:41 Unnecessary Roughness on the 49ers (Chase Lucas), 15 yards +5% JAX +1.5 pts
Q4 4:38 Offensive Holding on the Jaguars (Brian Thomas), 10 yards +1% SF +0.8 pts

Jaguars penalties, every game · 49ers penalties, every game · All teams, 2025

When it happened

49ers’ chance of winning

As low as 0% and as high as 68%. 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 Jaguars were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:31 The 49ers converted 3rd & 73rd & 4th downs · 33% expected +10% SF SF: Field goal
2 Q1 3:49 The Jaguars converted 4th & 13rd & 4th downs · 73% expected +9% JAX JAX: Punt
3 Q2 13:33 The 49ers converted 3rd & 43rd & 4th downs · 45% expected +10% SF SF: Turnover
4 Q2 11:35 The Jaguars converted 3rd & 153rd & 4th downs · 20% expected +11% JAX JAX: Touchdown
5 Q3 8:18 Defensive Pass Interference on the 49ers (Upton Stout), 13 yards, wiping out the playJudgment calls · 2 flags in 119 snaps before, position avg 1 per 213False Start on the Jaguars, 5 yardsPre-snap flags +24% JAX JAX: Punt
6 Q3 2:40 Return touchdown by the JaguarsSpecial teams +12% JAX JAX: Opp touchdown
7 Q4 3:35 C. Little missed 47-yard field goalKicks · 78% expected for him, 9 of 11 from 45+ before +16% SF JAX: End of game
8 Q4 2:52 The 49ers fumbled and the Jaguars recoveredFumble bounces · loose balls are close to 50/50 +10% JAX –

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.

  • Nick Bosa (SF DE), out (IR) · 1.1 pts
  • George Kittle (SF TE), out (IR) · 1.1 pts
  • Nick Bosa (SF DL), out (IR) · 0.9 pts
  • Renardo Green (SF CB), out · 0.5 pts
  • Malik Mustapha (SF FS), out (IR) · 0.3 pts
  • Ben Bartch (SF OL), out (IR) · 0.1 pts
  • Dyami Brown (JAX WR), 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

Jaguars 42% · 49ers 58%

Final margin
Jaguars by 5
Luck in points
10.7 for the Jaguars
Luck-adjusted margin
49ers by 5.7
Replay with same day's form
Jaguars 32% · 49ers 68% 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 4 2025 games · Jaguars · 49ers

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