luckadjusted
CFB Week 4 · 2026

Week 4 2025 · September 20, 2025

BYU at East Carolina, Week 4 2025: who deserved to win?

BYU beat East Carolina 34–13, and the replays lean its way: with the same day's form, it wins 7 of 10.

Before kickoff BYU was a 66% favorite. The biggest swing (Q2, 0:56 left): Return touchdown by BYU, worth 15 points of win probability to BYU.

Final

BYU Cougars 34
East Carolina Pirates 13

September 20, 2025 · Dowdy-Ficklen Stadium · Closing line: BYU −6.5

Luck index +34 BYU lucky · −34 East Carolina

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. BYU wins 7, East Carolina wins 3.

  1. 1 BYU 49 ECU 17
  2. 2 BYU 38 ECU 14
  3. 3 BYU 24 ECU 7
  4. 4 BYU 34 ECU 21
  5. 5 BYU 30 ECU 21
  6. 6 BYU 23 ECU 17
  7. 7 BYU 20 ECU 17
  8. 8 BYU 38 ECU 41
  9. 9 BYU 28 ECU 35
  10. 10 BYU 17 ECU 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, conversion and judgment call redrawn; everything else fixed. The narrowest view of luck.

How 4,000 replays ended

BYU wins 66% of them, East Carolina 34%, counting the 5% still level after regulation as half each. The line is what actually happened: BYU by 21.

Show as a table
Final margin in the replaysShare of replays
BYU by 17+26.2%
BYU by 9–1617.6%
BYU by 1–820.6%
Level after regulation5.2%
East Carolina by 1–816.1%
East Carolina by 9–168.3%
East Carolina by 17+5.9%

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 +5.0 points to BYU: the final margin was BYU by 21, without the luck BYU by 16. 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 what happened.

  • W. Ferrin, 40 yds made · 78% expected
  • N. Mazzie, 36 yds made · 78% expected
  • W. Ferrin, 23 yds made · 98% expected
  • N. Mazzie, 25 yds made · 90% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

Penalties: BYU 8 for 82 yards, East Carolina 11 for 76 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 10:44 False Start on BYU, 5 yards · pre-snap +1% ECU +0.5 pts
Q1 7:53 Offside on East Carolina, 5 yards · pre-snap +2% BYU +1.2 pts
Q1 7:43 Targeting on East Carolina, 15 yards +3% BYU +1.6 pts
Q1 4:15 False Start on East Carolina, 5 yards · pre-snap +1% BYU +0.7 pts
Q2 10:50 False Start on East Carolina, 5 yards · pre-snap 0% BYU +0.7 pts
Q2 9:28 Holding on East Carolina, 10 yards, wiping out the play +5% BYU +2.0 pts
Q2 2:02 Holding on BYU, 10 yards +2% ECU +1.0 pts
Q3 8:10 False Start on East Carolina, 5 yards · pre-snap +1% BYU +0.7 pts
Q3 6:33 False Start on East Carolina, 5 yards · pre-snap 0% BYU +0.8 pts
Q3 5:58 False Start on East Carolina, 5 yards · pre-snap +1% BYU +0.9 pts
Q3 3:46 Pass Interference on BYU, 4 yards +2% ECU +1.7 pts
Q3 3:41 Pass Interference on BYU, 13 yards +2% ECU +1.3 pts
Q3 3:41 False Start on East Carolina, 5 yards · pre-snap +1% BYU +0.9 pts
Q3 0:00 Holding on BYU, 10 yards, wiping out the play 0% ECU +1.3 pts
Q4 13:31 Personal Foul on BYU, 15 yards 0% ECU +1.8 pts
Q4 11:52 False Start on East Carolina, 1 yard · pre-snap 0% BYU +0.1 pts
Q4 7:27 Personal Foul on East Carolina, 15 yards 0% BYU +1.6 pts
Q4 7:13 Holding on BYU, 10 yards 0% ECU +1.2 pts
Q4 2:47 Unsportsmanlike Conduct on BYU, 15 yards 0% ECU +1.6 pts

When it happened

East Carolina’s chance of winning

Numbers mark the biggest luck moments, listed below.

Our in-game win probability: the score, the value of the possession and the time left, starting from the betting line. Overtime has no clock and is drawn at a fixed width. Shaded above the middle while East Carolina was ahead in it, below while BYU was.
#WhenWhat happenedWin probability forNext drive
1 Q1 13:48 East Carolina was stopped on 3rd & 13rd & 4th downs · 77% expected +4% BYU ECU: Turnover on downs
2 Q1 13:42 East Carolina was stopped on 4th & 53rd & 4th downs · 41% expected +4% BYU ECU: Punt
3 Q1 5:22 BYU was stopped on 4th & 13rd & 4th downs · 72% expected +4% ECU BYU: Punt
4 Q2 14:12 BYU converted 3rd & 43rd & 4th downs · 49% expected +3% BYU BYU: Field goal
5 Q2 9:58 East Carolina converted 3rd & 163rd & 4th downs · 19% expected +7% ECU ECU: Turnover
6 Q2 9:28 Holding on East Carolina, 10 yards, wiping out the playJudgment calls +5% BYU BYU: Punt
7 Q2 8:16 East Carolina converted 3rd & 113rd & 4th downs · 25% expected +6% ECU ECU: Turnover
8 Q2 0:56 Return touchdown by BYUSpecial teams +15% BYU BYU: Punt

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

BYU 100% · East Carolina 0%

Final margin
BYU by 21
Luck in points
5.0 for BYU
Luck-adjusted margin
BYU by 16.0
Replay with same day's form
BYU 66% · East Carolina 34% unchanged: why
How much of each is luck?

0% treats it as skill, 100% as pure luck. The tick is our fit.

What counts

None by default: our tests measured no carryover after a lucky break. Slide it up to count a break for more than its own swing. 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 expected points from CollegeFootballData.com via cfbfastR; win probability from our own model of the score, the possession and the betting line; kicks valued against each kicker’s own record. College play-by-play has no charting of drops or interception-worthy throws and no injury reports, so those kinds of luck aren’t counted here.

Methodology and validation · All Week 4 2025 games · BYU · East Carolina

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