luckadjusted

Week 1 2021 · September 12, 2021

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

Steelers at Bills, Week 1 2021: who deserved to win?

The Steelers beat the Bills 23–16, but it was a coin flip: replayed with the way both teams played, the Steelers win 6 of 10. Luck ran their way: judgment calls alone were worth 41 points of win probability to the Steelers.

Before kickoff the Bills were 68% favorites. The game turned on a luck play (Q4, 12:16 left): Defensive Pass Interference on the Bills, 26 yards, worth 19 points of win probability to the Steelers.

Final

Pittsburgh Steelers 23
Buffalo Bills 16

September 12, 2021 · New Era Field · Closing line: Bills −6.5

Luck index +44 Steelers lucky · −44 Bills

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 6, Bills win 4.

  1. 1 PIT 27 BUF 2
  2. 2 PIT 24 BUF 9
  3. 3 PIT 23 BUF 12
  4. 4 PIT 24 BUF 17
  5. 5 PIT 7 BUF 2
  6. 6 PIT 16 BUF 14
  7. 7 PIT 20 BUF 22
  8. 8 PIT 17 BUF 23
  9. 9 PIT 6 BUF 17
  10. 10 PIT 10 BUF 30

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

Steelers win 56% of them, Bills 44%, counting the 5% 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+11.7%
Steelers by 9–1616.0%
Steelers by 1–822.7%
Level after regulation5.3%
Bills by 1–822.5%
Bills by 9–1613.7%
Bills by 17+8.1%

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 +11.7 points to the Steelers: the final margin was Steelers by 7, without the luck Bills by 4.7. 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.

  • T. Bass, 37 yds made · 88% expected
  • C. Boswell, 24 yds made · 99% expected
  • C. Boswell, 20 yds made · 100% expected
  • T. Bass, 25 yds made · 97% expected
  • C. Boswell, 45 yds made · 77% expected
  • T. Bass, 42 yds made · 80% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Steelers 5 for 32 yards, Bills 8 for 81 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 9:28 Offensive Holding on the Bills, 10 yards, wiping out the play +6% PIT +2.1 pts
Q1 6:33 Offensive Holding on the Bills, 10 yards, wiping out the play +6% PIT +1.8 pts
Q1 4:26 Unsportsmanlike Conduct on the Steelers (Chase Claypool), 12 yards +2% BUF +1.2 pts
Q2 10:08 False Start on the Steelers, 4 yards · pre-snap +2% BUF +0.7 pts
Q2 4:48 Offensive Holding on the Bills, 10 yards +3% PIT +0.8 pts
Q2 2:36 Defensive Offside on the Steelers (Alex Highsmith), 5 yards · pre-snap 0% BUF +0.2 pts
Q3 13:56 Defensive Holding on the Bills (Tre'Davious White), 5 yards, wiping out the play +11% PIT +3.4 pts
Q4 12:16 Defensive Pass Interference on the Bills, 26 yards +19% PIT +3.1 pts
Q4 5:23 Defensive Holding on the Bills, 5 yards 0% PIT +0.4 pts
Q4 4:00 False Start on the Steelers (JuJu Smith-Schuster), 6 yards · pre-snap +1% BUF +0.8 pts
Q4 1:47 False Start on the Bills (Emmanuel Sanders), 5 yards · pre-snap 0% PIT +0.1 pts
Q4 0:59 Defensive Offside on the Steelers (Melvin Ingram), 5 yards · pre-snap 0% PIT +0.4 pts
Q4 0:54 Offensive Holding on the Bills, 10 yards 0% PIT +2.0 pts

Steelers penalties, every game · Bills penalties, every game · All teams, 2021

When it happened

Bills’ chance of winning

As low as 0% and as high as 86%. 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 Bills were ahead in it, below while the Steelers were.
#WhenWhat happenedWin probability forNext drive
1 Q2 8:47 The Bills were stopped on 3rd & 133rd & 4th downs · 24% expectedThe Bills fumbled and the Steelers recoveredFumble bounces · loose balls are close to 50/50 +14% PIT BUF: Touchdown
2 Q2 3:42 The Bills converted 3rd & 53rd & 4th downs · 41% expected +8% BUF BUF: Touchdown
3 Q3 13:56 Defensive Holding on the Bills (Tre'Davious White), 5 yards, wiping out the playJudgment calls · 14 flags in 2251 snaps before, position avg 1 per 213 +11% PIT PIT: Field goal
4 Q3 0:24 The Bills converted 3rd & 83rd & 4th downs · 32% expected +8% BUF BUF: Turnover on downs
5 Q4 13:46 The Bills were stopped on 4th & 13rd & 4th downs · 74% expected +11% PIT BUF: Opp touchdown
6 Q4 12:16 The game turned hereDefensive Pass Interference on the Bills, 26 yardsJudgment calls +19% PIT PIT: Touchdown
7 Q4 10:31 The Bills were stopped on 3rd & 63rd & 4th downs · 38% expected +9% PIT BUF: Opp touchdown
8 Q4 9:51 Blocked punt by the SteelersSpecial teams +16% PIT PIT: Opp touchdown

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.

  • Stephon Tuitt (PIT DE), out (IR) · 0.8 pts
  • Robert Spillane (PIT LB), 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 22% · Bills 78%

Final margin
Steelers by 7
Luck in points
11.7 for the Steelers
Luck-adjusted margin
Bills by 4.7
Replay with same day's form
Steelers 56% · Bills 44% 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 1 2021 games · Steelers · Bills

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