luckadjusted

Week 15 2020 · December 20, 2020

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

49ers at Cowboys, Week 15 2020: who deserved to win?

The Cowboys stole one. They beat the 49ers 41–33, but replayed with the way both teams actually played, the 49ers win 8 of 10. Luck ran their way: injuries alone were worth 5.2 points to the Cowboys.

Before kickoff the 49ers were 62% favorites. The biggest swing (Q3, 8:06 left): the Cowboys converted 3rd & 7, worth 15 points of win probability to the Cowboys.

Final

San Francisco 49ers 33
Dallas Cowboys 41

December 20, 2020 · AT&T Stadium · Closing line: 49ers −4

Luck index +82 Cowboys very lucky · −82 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. 49ers win 8, Cowboys win 2.

  1. 1 SF 43 DAL 9
  2. 2 SF 30 DAL 7
  3. 3 SF 30 DAL 12
  4. 4 SF 32 DAL 17
  5. 5 SF 35 DAL 23
  6. 6 SF 40 DAL 31
  7. 7 SF 36 DAL 30
  8. 8 SF 34 DAL 31
  9. 9 SF 31 DAL 34
  10. 10 SF 14 DAL 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

49ers win 82% of them, Cowboys 18%, counting the 1% still level after regulation as half each. The line is what actually happened: Cowboys by 8.

Show as a table
Final margin in the replaysShare of replays
49ers by 17+39.3%
49ers by 9–1619.8%
49ers by 1–821.3%
Level after regulation1.4%
Cowboys by 1–89.9%
Cowboys by 9–166.0%
Cowboys by 17+2.4%

Where the luck was

Take the luck out

The final margin was Cowboys by 8. Remove the luck, one kind at a time, and it becomes Cowboys by 1.8.

Each row takes one kind of luck out of the margin. Color shows which team it helped. Luck shares are the fitted ones (how much of each component is luck).

The kicks

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

  • G. Zuerlein, 48 yds made · 76% expected
  • G. Zuerlein, 60 yds missed · 58% expected
  • R. Gould, 41 yds made · 87% expected
  • G. Zuerlein, 46 yds made · 78% expected
  • R. Gould, 31 yds made · 96% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Cowboys’ chance of winning

As low as 49% 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 Cowboys were ahead in it, below while the 49ers were.
#WhenWhat happenedWin probability forNext drive
1 Q1 9:07 The 49ers were stopped on 3rd & 83rd & 4th downs · 33% expectedThe 49ers fumbled and the Cowboys recoveredFumble bounces · loose balls are close to 50/50 +11% DAL SF: Touchdown
2 Q2 0:48 The Cowboys converted 3rd & 183rd & 4th downs · 18% expected +7% DAL DAL: Missed field goal
3 Q2 0:27 G. Zuerlein missed 60-yard field goalKicks · 58% expected for him, 17 of 26 from 45+ before +9% SF DAL: Punt
4 Q3 8:06 The Cowboys converted 3rd & 73rd & 4th downs · 33% expected +15% DAL DAL: Touchdown
5 Q4 12:48 The Cowboys were stopped on 3rd & 43rd & 4th downs · 45% expected +7% SF DAL: Punt
6 Q4 10:34 The 49ers were stopped on 3rd & 63rd & 4th downs · 38% expected +10% DAL SF: Punt
7 Q4 10:12 G. Zuerlein made 46-yard field goalKicks · 78% expected for him, 17 of 27 from 45+ before +10% DAL DAL: Punt
8 Q4 3:37 Defensive Pass Interference on the Cowboys (Jourdan Lewis), 18 yardsJudgment calls · 5 flags in 1359 snaps before, position avg 1 per 207 +12% SF SF: 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.

  • Zack Martin (DAL G), out (IR) · 0.8 pts
  • Cameron Erving (DAL T), out (IR) · 0.6 pts
  • Ezekiel Elliott (DAL RB), out · 0.5 pts
  • Rashard Robinson (DAL CB), out · 0.3 pts
  • Cameron Erving (DAL G), out (IR) · 0.3 pts
  • Chris Jones (DAL P), out (IR) · 0.2 pts
  • Jimmy Garoppolo (SF QB), out (IR), replaced by n.mullens · 4.5 pts
  • George Kittle (SF TE), out (IR) · 1.1 pts
  • Deebo Samuel (SF WR), out · 1.1 pts
  • Jason Verrett (SF CB), out · 0.4 pts
  • Jamar Taylor (SF DB), out (IR) · 0.2 pts
  • Jaquiski Tartt (SF S), out (IR) · 0.2 pts
  • Tom Compton (SF OL), out (IR) · 0.1 pts
  • Hroniss Grasu (SF C), out · 0.1 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

49ers 16% · Cowboys 84%

Final margin
Cowboys by 8
Luck in points
6.2 for the Cowboys
Luck-adjusted margin
Cowboys by 1.8
Replay with same day's form
49ers 82% · Cowboys 18% 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 15 2020 games · 49ers · Cowboys

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