luckadjusted

Week 17 2020 · January 3, 2021

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

Vikings at Lions, Week 17 2020: who deserved to win?

The Vikings beat the Lions 37–35, but it was a coin flip: replayed with the way both teams played, the Vikings win 5 of 10. Luck ran their way: 3rd & 4th downs alone were worth 10 points of win probability to the Vikings.

Before kickoff the Vikings were 59% favorites. The biggest swing (Q1, 0:43 left): the Vikings converted 4th & 2, worth 14 points of win probability to the Vikings.

Final

Minnesota Vikings 37
Detroit Lions 35

January 3, 2021 · Ford Field · Closing line: Vikings −3

Luck index +54 Vikings lucky · −54 Lions

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. Vikings win 5, Lions win 5.

  1. 1 MIN 47 DET 24
  2. 2 MIN 30 DET 16
  3. 3 MIN 31 DET 23
  4. 4 MIN 31 DET 26
  5. 5 MIN 23 DET 20
  6. 6 MIN 28 DET 30
  7. 7 MIN 15 DET 20
  8. 8 MIN 19 DET 30
  9. 9 MIN 17 DET 33
  10. 10 MIN 10 DET 35

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

Vikings win 46% of them, Lions 54%, counting the 5% still level after regulation as half each. The line is what actually happened: Vikings by 2.

Show as a table
Final margin in the replaysShare of replays
Vikings by 17+11.1%
Vikings by 9–1613.0%
Vikings by 1–820.9%
Level after regulation5.4%
Lions by 1–820.8%
Lions by 9–1614.6%
Lions by 17+14.1%

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 +2.2 points to the Lions: the final margin was Vikings by 2, without the luck Vikings by 4.2. 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.

  • M. Prater, 54 yds made · 66% expected
  • D. Bailey, 46 yds missed · 78% expected
  • D. Bailey, 23 yds made · 98% expected
  • Extra point missed · 95% expected
  • Extra point missed · 95% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: Vikings 4 for 35 yards, Lions 7 for 51 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 14:29 Offensive Holding on the Vikings, 10 yards +4% DET +1.3 pts
Q2 14:26 Ineligible Downfield Pass on the Lions, 5 yards, wiping out the play 0% MIN +0.1 pts
Q2 4:00 False Start on the Vikings, 5 yards · pre-snap +3% DET +0.7 pts
Q2 0:14 Defensive Offside on the Lions (Everson Griffen), 6 yards · pre-snap +4% MIN +0.2 pts
Q3 12:51 Roughing the Passer on the Lions, 7 yards +4% MIN +1.0 pts
Q3 10:53 False Start on the Lions (Jesse James), 5 yards · pre-snap +1% MIN +1.0 pts
Q3 1:19 Defensive Pass Interference on the Lions (Amani Oruwariye), 18 yards +4% MIN +1.4 pts
Q4 15:00 Offensive Holding on the Vikings, 10 yards +4% DET +1.5 pts
Q4 11:18 Roughing the Passer on the Lions (Tracy Walker), 0 yards, wiping out the play +12% MIN +3.5 pts
Q4 10:32 Offensive Holding on the Lions (T.J. Hockenson), 10 yards +1% MIN +0.9 pts
Q4 4:16 Offensive Holding on the Vikings (Olabisi Johnson), 10 yards, wiping out the play +11% DET +2.0 pts

Vikings penalties, every game · Lions penalties, every game · All teams, 2020

When it happened

Lions’ chance of winning

As low as 0% and as high as 76%. 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 Lions were ahead in it, below while the Vikings were.
#WhenWhat happenedWin probability forNext drive
1 Q1 0:43 The Vikings converted 4th & 23rd & 4th downs · 64% expected +14% MIN MIN: Touchdown
2 Q2 2:58 D. Bailey missed 46-yard field goalKicks · 78% expected for him, 10 of 17 from 45+ before +14% DET MIN: Touchdown
3 Q3 9:49 The Lions were stopped on 3rd & 103rd & 4th downs · 31% expected +8% MIN DET: Touchdown
4 Q4 11:18 Roughing the Passer on the Lions (Tracy Walker), 0 yards, wiping out the playJudgment calls · 4 flags in 1651 snaps before, position avg 1 per 237 +12% MIN MIN: Touchdown
5 Q4 6:08 The Lions converted 3rd & 113rd & 4th downs · 29% expected +12% DET DET: Touchdown
6 Q4 4:26 The Lions’ two-point try failed3rd & 4th downs · 47% expected +12% MIN –
7 Q4 4:16 Offensive Holding on the Vikings (Olabisi Johnson), 10 yards, wiping out the playJudgment calls · 2 flags in 1011 snaps before, position avg 1 per 385 +11% DET –
8 Q4 2:28 The Vikings converted 4th & 13rd & 4th downs · 76% expected +12% MIN MIN: End of game

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.

  • Desmond Trufant (DET CB), out (IR) · 0.8 pts
  • Jamie Collins (DET LB), out · 0.5 pts
  • Tyrell Crosby (DET OL), out · 0.4 pts
  • Riley Reiff (MIN T), out (IR) · 0.9 pts
  • Kyle Rudolph (MIN TE), out (IR) · 0.7 pts
  • Eric Kendricks (MIN LB), out · 0.5 pts
  • Cameron Dantzler (MIN CB), out · 0.5 pts
  • Dalvin Cook (MIN RB), out · 0.4 pts
  • Chris Jones (MIN CB), out · 0.3 pts
  • Jalyn Holmes (MIN DE), out · 0.3 pts
  • Ifeadi Odenigbo (MIN DE), out · 0.3 pts
  • Kris Boyd (MIN CB), out (IR) · 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

Vikings 59% · Lions 41%

Final margin
Vikings by 2
Luck in points
2.2 for the Lions
Luck-adjusted margin
Vikings by 4.2
Replay with same day's form
Vikings 46% · Lions 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 17 2020 games · Vikings · Lions

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