luckadjusted

Week 15 2019 · December 15, 2019

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

Falcons at 49ers, Week 15 2019: who deserved to win?

The Falcons beat the 49ers 29–22 and were the better team on the day: replayed with the same form, they win 7 of 10. The 49ers had the bounces: judgment calls alone were worth 3.5 points to the 49ers.

An off day for the 49ers: their offense played far below its usual level. In a fresh game against the Falcons they would win 75% of the time; with this day’s form, 33%. The numbers

Before kickoff the 49ers were 78% favorites. The biggest swing (Q4, 0:02 left): Return touchdown by the Falcons, worth 45 points of win probability to the Falcons.

Final

Atlanta Falcons 29
San Francisco 49ers 22

December 15, 2019 · Levi's Stadium · Closing line: 49ers −10.5

Luck index +33 Falcons lucky · −33 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. Falcons win 7, 49ers win 3.

  1. 1 ATL 38 SF 10
  2. 2 ATL 36 SF 16
  3. 3 ATL 23 SF 9
  4. 4 ATL 31 SF 21
  5. 5 ATL 24 SF 17
  6. 6 ATL 31 SF 27
  7. 7 ATL 15 SF 13
  8. 8 ATL 16 SF 18
  9. 9 ATL 21 SF 28
  10. 10 ATL 11 SF 27

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 49ers

Their offense played far below its usual level. In a fresh game against the Falcons they would win 75% of the time; with this day’s form, 33%.

42 points apart for the 49ers: the gap is how differently this game went from what the two teams usually are.

UnitThis gameUsual levelBetter or worse than usual
Falcons offenseEPA per play gained +0.08 +0.13 worse by 0.05
Falcons defenseEPA per play allowed +0.02 +0.17 better by 0.15
49ers offenseEPA per play gained +0.02 +0.16 worse by 0.14
49ers defenseEPA per play allowed +0.08 +0.05 worse by 0.03

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

Falcons win 67% of them, 49ers 33%, counting the 2% still level after regulation as half each. The line is what actually happened: Falcons by 7.

Show as a table
Final margin in the replaysShare of replays
Falcons by 17+18.5%
Falcons by 9–1620.0%
Falcons by 1–827.5%
Level after regulation2.5%
49ers by 1–817.6%
49ers by 9–168.9%
49ers by 17+5.0%

Where the luck was

Take the luck out

The final margin was Falcons by 7. Remove the luck, one kind at a time, and it becomes Falcons by 7.4.

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.

  • Y. Koo, 43 yds made · 83% expected
  • R. Gould, 22 yds made · 98% expected
  • R. Gould, 46 yds made · 73% expected
  • R. Gould, 43 yds made · 82% expected
  • Extra point missed · 93% 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 90%. 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 Falcons were.
#WhenWhat happenedWin probability forNext drive
1 Q1 1:12 Roughing the Passer on the Falcons (Adrian Clayborn), 15 yardsJudgment calls · 1 flag in 360 snaps before, position avg 1 per 249 +8% SF SF: Touchdown
2 Q3 5:20 R. Gould made 46-yard field goalKicks · 73% expected for him, 1 of 7 from 45+ before +8% SF SF: Turnover
3 Q3 0:44 The 49ers fumbled and the Falcons recoveredFumble bounces · loose balls are close to 50/50 +8% ATL SF: Punt
4 Q4 11:00 The Falcons fumbled and the 49ers recoveredFumble bounces · loose balls are close to 50/50 +9% SF ATL: Touchdown
5 Q4 5:28 Defensive Pass Interference on the 49ers (Jimmie Ward), 32 yardsJudgment calls · 0 flags in 689 snaps before, position avg 1 per 465 +11% ATL ATL: Touchdown
6 Q4 1:52 R. Gould made 43-yard field goalKicks · 82% expected for him +11% ATL SF: Touchdown
7 Q4 0:05 The Falcons converted 3rd & 53rd & 4th downs · 33% expected +30% ATL ATL: Touchdown
8 Q4 0:02 The Falcons’ two-point try failed3rd & 4th downs · 47% expectedThe 49ers fumbled and the Falcons recoveredFumble bounces · loose balls are close to 50/50Return touchdown by the FalconsSpecial teams +45% ATL –

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.

  • Richard Sherman (SF CB), out · 1.6 pts
  • Weston Richburg (SF C), out (IR) · 0.6 pts
  • K'Waun Williams (SF CB), out · 0.4 pts
  • Jaquiski Tartt (SF SS), out · 0.4 pts
  • Kwon Alexander (SF LB), out (IR) · 0.3 pts
  • Desmond Trufant (ATL CB), out (IR) · 0.8 pts
  • Calvin Ridley (ATL WR), out (IR) · 0.7 pts
  • James Carpenter (ATL G), out · 0.3 pts
  • Jamon Brown (ATL G), 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

Falcons 87% · 49ers 13%

Final margin
Falcons by 7
Luck in points
0.4 for the 49ers
Luck-adjusted margin
Falcons by 7.4
Replay with same day's form
Falcons 67% · 49ers 33% 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 2019 games · Falcons · 49ers

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