luckadjusted

Week 2 2020 · September 20, 2020

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

Giants at Bears, Week 2 2020: who deserved to win?

The Bears beat the Giants 17–13, but the Giants played well enough to win it: they take 8 of 10 replays with the same day's form. Luck ran their way: judgment calls alone were worth 12 points of win probability to the Bears.

The Bears won on an off day: they played far below what the matchup promised. In a fresh game against the Giants they would win 64% of the time; with this day’s form, 22%. The numbers

Before kickoff the Bears were 63% favorites. The biggest swing (Q4, 0:04 left): Offensive Pass Interference on the Giants (Golden Tate), 0 yards, worth 45 points of win probability to the Bears.

Final

New York Giants 13
Chicago Bears 17

September 20, 2020 · Soldier Field · Closing line: Bears −4.5

Luck index +78 Bears very lucky · −78 Giants

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. Giants win 8, Bears win 2.

  1. 1 NYG 33 CHI 7
  2. 2 NYG 26 CHI 7
  3. 3 NYG 17 CHI 2
  4. 4 NYG 26 CHI 13
  5. 5 NYG 27 CHI 17
  6. 6 NYG 16 CHI 9
  7. 7 NYG 10 CHI 7
  8. 8 NYG 21 CHI 19
  9. 9 NYG 9 CHI 12
  10. 10 NYG 13 CHI 24

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.

The Bears won on an off day

They played far below what the matchup promised. In a fresh game against the Giants they would win 64% of the time; with this day’s form, 22%.

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

UnitThis gameUsual levelBetter or worse than usual
Giants offenseEPA per play gained +0.02 +0.09 worse by 0.06
Giants defenseEPA per play allowed +0.17 +0.14 worse by 0.03
Bears offenseEPA per play gained +0.17 +0.05 better by 0.12
Bears defenseEPA per play allowed +0.02 +0.06 better 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

Giants win 78% of them, Bears 22%, counting the 4% still level after regulation as half each. The line is what actually happened: Bears by 4.

Show as a table
Final margin in the replaysShare of replays
Giants by 17+24.8%
Giants by 9–1623.2%
Giants by 1–826.9%
Level after regulation4.0%
Bears by 1–813.2%
Bears by 9–166.0%
Bears by 17+2.1%

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 +2.6 points to the Giants: the final margin was Bears by 4, without the luck Bears by 6.6. 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.

  • C. Santos, 34 yds made · 92% expected
  • G. Gano, 57 yds missed · 56% expected
  • G. Gano, 39 yds made · 87% expected
  • G. Gano, 37 yds made · 89% expected
  • C. Santos, 50 yds missed · 66% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Giants 3 for 10 yards, Bears 5 for 48 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 11:10 Neutral Zone Infraction on the Giants (Kyler Fackrell), 5 yards · pre-snap +2% CHI +0.6 pts
Q2 15:00 Illegal Use of Hands on the Bears (Akiem Hicks), 5 yards +2% NYG +0.8 pts
Q3 12:23 Illegal Touch Kick on the Giants (Brandon Williams), 5 yards +1% CHI +0.5 pts
Q3 1:42 Unnecessary Roughness on the Bears (Roquan Smith), 15 yards +4% NYG +1.8 pts
Q3 1:20 Defensive Offside on the Bears, 5 yards, wiping out the play · pre-snap +1% CHI +0.3 pts
Q4 10:12 Defensive Pass Interference on the Bears (Eddie Jackson), 8 yards, wiping out the play +21% NYG +6.4 pts
Q4 4:56 Chop Block on the Bears, 15 yards, wiping out the play +8% NYG +2.3 pts
Q4 0:04 Offensive Pass Interference on the Giants (Golden Tate), 0 yards +45% CHI +2.8 pts

Giants penalties, every game · Bears penalties, every game · All teams, 2020

When it happened

Bears’ chance of winning

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 Bears were ahead in it, below while the Giants were.
#WhenWhat happenedWin probability forNext drive
1 Q1 7:38 The Bears converted 3rd & 73rd & 4th downs · 31% expected +10% CHI CHI: Touchdown
2 Q1 6:19 The Giants were stopped on 3rd & 63rd & 4th downs · 38% expectedThe Giants fumbled and the Bears recoveredFumble bounces · loose balls are close to 50/50 +15% CHI NYG: Punt
3 Q4 10:12 Defensive Pass Interference on the Bears (Eddie Jackson), 8 yards, wiping out the playJudgment calls · 2 flags in 1165 snaps before, position avg 1 per 237 +21% NYG NYG: Field goal
4 Q4 4:56 Chop Block on the Bears, 15 yards, wiping out the playJudgment calls +8% NYG NYG: End of game
5 Q4 2:07 C. Santos missed 50-yard field goalKicks · 66% expected for him, 3 of 6 from 45+ before +14% NYG –
6 Q4 1:55 The Giants converted 3rd & 103rd & 4th downs · 28% expected +16% NYG NYG: End of game
7 Q4 0:45 The Giants converted 4th & 43rd & 4th downs · 46% expected +21% NYG NYG: End of game
8 Q4 0:04 Offensive Pass Interference on the Giants (Golden Tate), 0 yardsJudgment calls · 1 flag in 656 snaps before, position avg 1 per 385 +45% CHI –

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.

  • David Mayo (NYG LB), out (IR) · 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

Giants 23% · Bears 77%

Final margin
Bears by 4
Luck in points
2.6 for the Giants
Luck-adjusted margin
Bears by 6.6
Replay with same day's form
Giants 78% · Bears 22% 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 2 2020 games · Giants · Bears

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