luckadjusted
NFL Week 9 · 2026

Week 17 2023 · December 31, 2023

Steelers at Seahawks, Week 17 2023: who deserved to win?

The Steelers beat the Seahawks 30–23, and the replays lean their way: with the same day's form, they win 8 of 10.

An off day for the Seahawks: their defense played far below its usual level. In a fresh game against the Steelers they would win 60% of the time; with this day’s form, 25%. The numbers

Before kickoff the Seahawks were 63% favorites. The biggest swing (Q2, 5:36 left): the Seahawks converted 3rd & 11, worth 8 points of win probability to the Seahawks.

Final

Pittsburgh Steelers 30
Seattle Seahawks 23

December 31, 2023 · Lumen Field · Closing line: Seahawks −4.5

Luck index +25 Steelers about even · −25 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. Steelers win 8, Seahawks win 2.

  1. 1 PIT 31 SEA 3
  2. 2 PIT 30 SEA 10
  3. 3 PIT 37 SEA 21
  4. 4 PIT 30 SEA 17
  5. 5 PIT 34 SEA 24
  6. 6 PIT 32 SEA 24
  7. 7 PIT 28 SEA 23
  8. 8 PIT 16 SEA 13
  9. 9 PIT 23 SEA 26
  10. 10 PIT 20 SEA 33

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.

An off day for the Seahawks

Their defense played far below its usual level. In a fresh game against the Steelers they would win 60% of the time; with this day’s form, 25%.

35 points apart for the Seahawks: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Steelers offenseEPA per play gained +0.30 +0.04 better by 0.27
Steelers defenseEPA per play allowed +0.25 +0.08 worse by 0.16
Seahawks offenseEPA per play gained +0.25 +0.09 better by 0.16
Seahawks defenseEPA per play allowed +0.30 +0.12 worse by 0.18

EPA (expected points added) per play on competitive snaps, turnovers left out because they are valued as luck. Usual level: the team’s earlier games this season plus half of last season, pulled toward the league average. One team’s defense and the other team’s offense are the same snaps, so one game can’t fully say whose day it was; it shows how far this one was from both teams’ norms.

How 4,000 replays ended

Steelers win 75% of them, Seahawks 25%, counting the 4% still level after regulation as half each. The line is what actually happened: Steelers by 7.

Show as a table
Final margin in the replaysShare of replays
Steelers by 17+24.3%
Steelers by 9–1622.7%
Steelers by 1–825.0%
Level after regulation3.7%
Seahawks by 1–814.6%
Seahawks by 9–166.3%
Seahawks by 17+3.4%

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 +0.2 points to the Seahawks: the final margin was Steelers by 7, without the luck Steelers by 7.2. 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.

  • C. Boswell, 39 yds made · 91% expected
  • J. Myers, 43 yds made · 85% expected
  • J. Myers, 42 yds made · 86% expected
  • C. Boswell, 26 yds made · 99% expected
  • C. Boswell, 21 yds made · 100% expected
  • J. Myers, 24 yds made · 98% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Steelers 2 for 10 yards, Seahawks 4 for 25 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
Q1 4:11 Illegal Motion on the Steelers (Pat Freiermuth), 5 yards, wiping out the play · pre-snap +4% SEA +1.6 pts
Q2 8:26 False Start on the Seahawks (Colby Parkinson), 5 yards · pre-snap +5% PIT +0.7 pts
Q2 5:52 False Start on the Seahawks, 5 yards · pre-snap +3% PIT +0.6 pts
Q3 12:35 Offensive Holding on the Seahawks (D.K. Metcalf), 10 yards +3% PIT +0.6 pts
Q3 10:41 False Start on the Steelers (Connor Heyward), 5 yards · pre-snap +2% SEA +0.9 pts
Q4 3:18 False Start on the Seahawks, 5 yards · pre-snap +1% PIT +0.6 pts

Steelers penalties, every game · Seahawks penalties, every game · All teams, 2023

When it happened

Seahawks’ chance of winning

As low as 0% and as high as 71%. 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 Seahawks were ahead in it, below while the Steelers were.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:42 The Steelers converted 3rd & 53rd & 4th downs · 45% expected +5% PIT PIT: Turnover on downs
2 Q2 11:09 The Steelers were stopped on 3rd & 83rd & 4th downs · 36% expected +7% SEA PIT: Field goal
3 Q2 8:26 False Start on the Seahawks (Colby Parkinson), 5 yardsPre-snap flags · 7 flags in 1668 snaps before, position avg 1 per 286 +5% PIT PIT: Touchdown
4 Q2 5:36 The Seahawks converted 3rd & 113rd & 4th downs · 26% expected +8% SEA SEA: Touchdown
5 Q2 4:12 The Steelers converted 3rd & 43rd & 4th downs · 50% expected +7% PIT PIT: Touchdown
6 Q3 10:51 J. Myers made a 43-yard field goalKicks · 85% expected for him +5% SEA SEA: Punt
7 Q4 11:35 The Steelers converted 3rd & 63rd & 4th downs · 41% expected +6% PIT PIT: Field goal
8 Q4 7:07 The Seahawks fumbled and the Steelers recoveredFumble bounces · loose balls are close to 50/50 +6% PIT SEA: Field goal

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.

  • Jamal Adams (SEA SS), out (IR) · 0.7 pts
  • Jordyn Brooks (SEA LB), out · 0.5 pts
  • Phil Haynes (SEA G), out (IR) · 0.2 pts
  • Kenny Pickett (PIT QB), out, replaced by m.rudolph · 1.6 pts
  • Minkah Fitzpatrick (PIT FS), out · 0.9 pts
  • Elandon Roberts (PIT LB), out · 0.4 pts
  • Keanu Neal (PIT FS), out (IR) · 0.4 pts
  • Damontae Kazee (PIT SS), out (IR) · 0.3 pts
  • Trenton Thompson (PIT SS), 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

Steelers 86% · Seahawks 14%

Final margin
Steelers by 7
Luck in points
0.2 for the Seahawks
Luck-adjusted margin
Steelers by 7.2
Replay with same day's form
Steelers 75% · Seahawks 25% 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; injuries from snap counts and injury reports.

Methodology and validation · All Week 17 2023 games · Steelers · Seahawks

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