luckadjusted

Week 7 2021 · October 24, 2021

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

Colts at 49ers, Week 7 2021: who deserved to win?

The Colts beat the 49ers 30–18, but it was a coin flip: replayed with the way both teams played, the Colts win 5 of 10. Luck ran their way: judgment calls alone were worth 24 points of win probability to the Colts.

Before kickoff the 49ers were 60% favorites. The biggest swing (Q3, 4:46 left): the 49ers were stopped on 3rd & 5, worth 22 points of win probability to the Colts.

Final

Indianapolis Colts 30
San Francisco 49ers 18

October 24, 2021 · Levi's Stadium · Closing line: 49ers −3.5

Luck index +54 Colts lucky · −54 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. Colts win 5, 49ers win 5.

  1. 1 IND 45 SF 23
  2. 2 IND 38 SF 24
  3. 3 IND 22 SF 12
  4. 4 IND 28 SF 23
  5. 5 IND 29 SF 27
  6. 6 IND 13 SF 15
  7. 7 IND 24 SF 30
  8. 8 IND 24 SF 33
  9. 9 IND 17 SF 31
  10. 10 IND 6 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

Colts win 46% of them, 49ers 54%, counting the 5% still level after regulation as half each. The line is what actually happened: Colts by 12.

Show as a table
Final margin in the replaysShare of replays
Colts by 17+11.9%
Colts by 9–1614.0%
Colts by 1–819.8%
Level after regulation4.5%
49ers by 1–820.3%
49ers by 9–1615.1%
49ers by 17+14.4%

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 +14.6 points to the Colts: the final margin was Colts by 12, without the luck 49ers by 2.6. 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.

  • J. Slye, 34 yds made · 91% expected
  • J. Slye, 56 yds made · 54% expected
  • M. Badgley, 42 yds made · 79% expected
  • Extra point missed · 93% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Colts 6 for 45 yards, 49ers 7 for 122 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 2:18 Defensive Pass Interference on the 49ers, 40 yards +11% IND +3.9 pts
Q2 2:00 Defensive Pass Interference on the 49ers, 19 yards +8% IND +2.8 pts
Q2 0:54 False Start on the 49ers, 5 yards · pre-snap +3% IND +0.3 pts
Q3 8:53 Delay of Game on the Colts, 5 yards · pre-snap +2% SF +0.5 pts
Q3 6:41 False Start on the 49ers (Jamycal Hasty), 5 yards · pre-snap +2% IND +0.7 pts
Q3 4:38 Offensive Holding on the Colts, 10 yards, wiping out the play +9% SF +2.3 pts
Q3 4:02 Defensive Pass Interference on the 49ers (Jaquiski Tartt), 38 yards +10% IND +4.2 pts
Q3 3:45 Ineligible Downfield Pass on the 49ers, 5 yards, wiping out the play +4% IND +1.5 pts
Q3 3:13 Offensive Holding on the 49ers (Ross Dwelley), 10 yards, wiping out the play +6% IND +1.8 pts
Q3 1:24 Offensive Holding on the Colts, 10 yards +3% SF +1.3 pts
Q4 10:28 Delay of Game on the Colts, 5 yards · pre-snap +4% SF +0.7 pts
Q4 8:14 Offensive Holding on the Colts, 10 yards +6% SF +1.7 pts
Q4 1:05 False Start on the Colts (Jack Doyle), 5 yards · pre-snap 0% SF +0.1 pts

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

When it happened

49ers’ chance of winning

As low as 0% and as high as 80%. 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 Colts were.
#WhenWhat happenedWin probability forNext drive
1 Q1 7:24 The Colts converted 3rd & 113rd & 4th downs · 22% expected +10% IND IND: Touchdown
2 Q1 2:18 Defensive Pass Interference on the 49ers, 40 yardsJudgment calls +11% IND IND: Turnover
3 Q2 3:10 The 49ers were stopped on 3rd & 123rd & 4th downs · 23% expectedThe 49ers fumbled and the Colts recoveredFumble bounces · loose balls are close to 50/50 +13% IND SF: End of half
4 Q3 11:28 The Colts converted 4th & 13rd & 4th downs · 70% expectedThe Colts fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +13% IND IND: Punt
5 Q3 4:46 The 49ers were stopped on 3rd & 53rd & 4th downs · 40% expectedThe 49ers fumbled and the Colts recoveredFumble bounces · loose balls are close to 50/50 +22% IND SF: Punt
6 Q3 4:38 Offensive Holding on the Colts, 10 yards, wiping out the playJudgment calls +9% SF SF: Punt
7 Q3 4:02 Defensive Pass Interference on the 49ers (Jaquiski Tartt), 38 yardsJudgment calls · 1 flag in 1707 snaps before, position avg 1 per 420 +10% IND IND: Touchdown
8 Q4 5:26 The 49ers were stopped on 3rd & 33rd & 4th downs · 50% expected +16% IND 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.

  • Trent Williams (SF T), out · 1.2 pts
  • George Kittle (SF TE), out (IR) · 1.1 pts
  • Deommodore Lenoir (SF CB), out · 0.5 pts
  • Jason Verrett (SF CB), out (IR) · 0.4 pts
  • Dre Greenlaw (SF LB), out (IR) · 0.3 pts
  • Richie James (SF WR), out (IR) · 0.3 pts
  • Robbie Gould (SF K), out (IR) · 0.3 pts
  • Tarvarius Moore (SF DB), out (IR) · 0.3 pts
  • Javon Kinlaw (SF DT), out · 0.3 pts
  • Justin Skule (SF OL), out (IR) · 0.3 pts
  • T.Y. Hilton (IND WR), out · 0.9 pts
  • Julian Blackmon (IND FS), out (IR) · 0.4 pts
  • Julian Blackmon (IND S), out (IR) · 0.4 pts
  • T.J. Carrie (IND CB), out (IR) · 0.4 pts
  • Rock Ya-Sin (IND CB), out · 0.4 pts
  • Rodrigo Blankenship (IND K), out (IR) · 0.3 pts
  • Parris Campbell (IND WR), out (IR) · 0.2 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

Colts 42% · 49ers 58%

Final margin
Colts by 12
Luck in points
14.6 for the Colts
Luck-adjusted margin
49ers by 2.6
Replay with same day's form
Colts 46% · 49ers 54% 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 7 2021 games · Colts · 49ers

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