luckadjusted

Week 1 2020 · September 13, 2020

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

Cardinals at 49ers, Week 1 2020: who deserved to win?

The Cardinals beat the 49ers 24–20, 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: 3rd & 4th downs alone were worth 5.0 points to the Cardinals.

Before kickoff the 49ers were 70% favorites. The biggest swing (Q4, 9:37 left): Defensive Pass Interference on the Cardinals (Jordan Hicks), 27 yards, wiping out the play, worth 44 points of win probability to the 49ers.

Final

Arizona Cardinals 24
San Francisco 49ers 20

September 13, 2020 · Levi's Stadium · Closing line: 49ers −7

Luck index +74 Cardinals very lucky · −74 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. Cardinals win 3, 49ers win 7.

  1. 1 ARI 41 SF 24
  2. 2 ARI 27 SF 20
  3. 3 ARI 37 SF 34
  4. 4 ARI 21 SF 23
  5. 5 ARI 13 SF 17
  6. 6 ARI 27 SF 33
  7. 7 ARI 21 SF 30
  8. 8 ARI 13 SF 27
  9. 9 ARI 17 SF 37
  10. 10 ARI 3 SF 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

Cardinals win 26% of them, 49ers 74%, counting the 3% still level after regulation as half each. The line is what actually happened: Cardinals by 4.

Show as a table
Final margin in the replaysShare of replays
Cardinals by 17+3.9%
Cardinals by 9–167.8%
Cardinals by 1–814.3%
Level after regulation3.5%
49ers by 1–824.1%
49ers by 9–1620.5%
49ers by 17+25.9%

Where the luck was

Take the luck out

The final margin was Cardinals by 4. Remove the luck, one kind at a time, and it becomes Cardinals by 6.9.

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.

  • R. Gould, 52 yds made · 64% expected
  • Z. Gonzalez, 52 yds missed · 67% expected
  • R. Gould, 24 yds made · 98% expected
  • Z. Gonzalez, 56 yds made · 60% expected
  • Z. Gonzalez, 49 yds missed · 72% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

49ers’ chance of winning

As low as 0% and as high as 82%. 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 Cardinals were.
#WhenWhat happenedWin probability forNext drive
1 Q2 7:33 Z. Gonzalez missed 52-yard field goalKicks · 67% expected for him, 5 of 7 from 45+ before +12% SF ARI: Turnover
2 Q3 11:37 The Cardinals converted 3rd & 173rd & 4th downs · 18% expected +16% ARI ARI: Missed field goal
3 Q3 9:54 Z. Gonzalez missed 49-yard field goalKicks · 72% expected for him, 6 of 9 from 45+ before +10% SF ARI: Punt
4 Q4 9:37 Defensive Pass Interference on the Cardinals (Jordan Hicks), 27 yards, wiping out the playJudgment calls · 4 flags in 1231 snaps before, position avg 1 per 395 +44% SF SF: Touchdown
5 Q4 8:42 The 49ers converted 3rd & 53rd & 4th downs · 35% expected +12% SF SF: Touchdown
6 Q4 5:27 The Cardinals converted 3rd & 63rd & 4th downs · 36% expected +23% ARI ARI: Touchdown
7 Q4 0:47 The 49ers were stopped on 3rd & 53rd & 4th downs · 43% expected +11% ARI SF: Turnover on downs
8 Q4 0:37 The 49ers were stopped on 4th & 53rd & 4th downs · 42% expected +39% ARI –

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.

  • Deebo Samuel (SF WR), out (IR) · 1.1 pts
  • Ben Garland (SF C), 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

Cardinals 80% · 49ers 20%

Final margin
Cardinals by 4
Luck in points
2.9 for the 49ers
Luck-adjusted margin
Cardinals by 6.9
Replay with same day's form
Cardinals 26% · 49ers 74% 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 2020 games · Cardinals · 49ers

More from Week 1 2020