luckadjusted
NFL Week 9 · 2026

Week 17 2021 · January 2, 2022

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

Texans at 49ers, Week 17 2021: who deserved to win?

The 49ers beat the Texans 23–7, and the replays back it up: with the way both teams actually played, the 49ers win 10 of 10.

Before kickoff the 49ers were 85% favorites. The biggest swing (Q3, 0:20 left): Offensive Holding on the Texans (Pharaoh Brown), 10 yards, wiping out the play, worth 26 points of win probability to the 49ers.

Final

Houston Texans 7
San Francisco 49ers 23

January 2, 2022 · Levi's Stadium · Closing line: 49ers −14

Luck index +1 49ers about even · −1 Texans

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. Texans win 0, 49ers win 10.

  1. 1 HOU 17 SF 21
  2. 2 HOU 17 SF 27
  3. 3 HOU 15 SF 28
  4. 4 HOU 7 SF 24
  5. 5 HOU 14 SF 34
  6. 6 HOU 6 SF 29
  7. 7 HOU 7 SF 33
  8. 8 HOU 7 SF 37
  9. 9 HOU 13 SF 47
  10. 10 HOU 0 SF 43

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

Texans win 1% of them, 49ers 99%. The line is what actually happened: 49ers by 16.

Show as a table
Final margin in the replaysShare of replays
Texans by 17+0.0%
Texans by 9–160.2%
Texans by 1–80.8%
Level after regulation0.3%
49ers by 1–83.0%
49ers by 9–1610.3%
49ers by 17+85.5%

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 +5.4 points to the Texans: the final margin was 49ers by 16, without the luck 49ers by 21.4. 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.

  • R. Gould, 37 yds made · 90% expected
  • K. Fairbairn, 45 yds missed · 77% expected
  • R. Gould, 27 yds made · 96% expected
  • R. Gould, 36 yds made · 91% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Texans 5 for 67 yards, 49ers 7 for 111 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 half toward luck; pre-snap fouls, which repeat, don’t count. How calls are valued

WhenFlagWin probability for
Q2 15:00 Offensive Holding on the 49ers, 10 yards +3% HOU +0.9 pts
Q2 9:24 Illegal Block Above the Waist on the Texans (Justin Reid), 10 yards +2% SF +0.9 pts
Q2 7:16 False Start on the Texans, 5 yards · pre-snap +3% SF +0.7 pts
Q2 0:38 Defensive Delay of Game on the Texans (Kamu Grugier-Hill), 5 yards · pre-snap +3% SF +0.8 pts
Q2 0:07 False Start on the 49ers, 5 yards · pre-snap +3% HOU +0.2 pts
Q3 9:43 Face Mask on the 49ers (Jaquiski Tartt), 15 yards +6% HOU +1.4 pts
Q3 8:14 Defensive Pass Interference on the Texans (Terrance Mitchell), 37 yards +13% SF +2.4 pts
Q3 0:20 Offensive Holding on the Texans (Pharaoh Brown), 10 yards, wiping out the play +26% SF +3.2 pts
Q4 14:23 Defensive Pass Interference on the 49ers (Josh Norman), 33 yards +15% HOU +3.4 pts
Q4 14:16 Defensive Pass Interference on the 49ers (Dontae Johnson), 23 yards +9% HOU +1.5 pts
Q4 9:49 Roughing the Passer on the 49ers (Arden Key), 15 yards +1% HOU +0.7 pts
Q4 3:33 Offensive Holding on the 49ers (Brandon Aiyuk), 10 yards, wiping out the play +1% HOU +3.1 pts

Texans penalties, every game · 49ers penalties, every game · All teams, 2021

When it happened

49ers’ chance of winning

As low as 27% 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 Texans were.
#WhenWhat happenedWin probability forNext drive
1 Q2 6:54 The Texans converted 3rd & 93rd & 4th downs · 29% expected +9% HOU HOU: Touchdown
2 Q3 11:17 The 49ers were stopped on 4th & 13rd & 4th downs · 75% expected +10% HOU SF: Touchdown
3 Q3 8:14 Defensive Pass Interference on the Texans (Terrance Mitchell), 37 yardsJudgment calls · 3 flags in 2367 snaps before, position avg 1 per 213 +13% SF SF: Touchdown
4 Q3 0:20 Offensive Holding on the Texans (Pharaoh Brown), 10 yards, wiping out the playJudgment calls · 17 flags in 1291 snaps before, position avg 1 per 269 +26% SF SF: Touchdown
5 Q4 14:23 Defensive Pass Interference on the 49ers (Josh Norman), 33 yardsJudgment calls · 12 flags in 1815 snaps before, position avg 1 per 213 +15% HOU HOU: Missed field goal
6 Q4 14:16 Defensive Pass Interference on the 49ers (Dontae Johnson), 23 yardsJudgment calls · 5 flags in 1135 snaps before, position avg 1 per 213 +9% HOU HOU: Missed field goal
7 Q4 12:50 The Texans were stopped on 3rd & 33rd & 4th downs · 52% expected +9% SF HOU: Missed field goal
8 Q4 12:08 K. Fairbairn missed a 45-yard field goalKicks · 77% expected for him, 15 of 26 from 45+ before +12% SF HOU: 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.

  • Jimmy Garoppolo (SF QB), out, replaced by t.lance · 7.3 pts
  • Emmanuel Moseley (SF CB), out (IR) · 0.6 pts
  • Talanoa Hufanga (SF SS), out · 0.4 pts
  • Azeez Al-Shaair (SF LB), out · 0.3 pts
  • Tytus Howard (HOU T), out (IR) · 0.8 pts
  • Maliek Collins (HOU DT), out · 0.4 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

Texans 0% · 49ers 100%

Final margin
49ers by 16
Luck in points
5.4 for the Texans
Luck-adjusted margin
49ers by 21.4
Replay with same day's form
Texans 1% · 49ers 99% unchanged: why
How much of each is luck?

0% treats it as skill, 100% as pure luck. The tick is our fit.

What counts

None by default: our tests measured no carryover after a lucky break. Slide it up to count a break for more than its own swing. 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 17 2021 games · Texans · 49ers

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