Week 4 2025 · September 20, 2025
Purdue at Notre Dame, Week 4 2025: who deserved to win?
Notre Dame beat Purdue 56–30, and the replays back it up: with the way both teams actually played, Notre Dame wins 10 of 10.
Before kickoff Notre Dame was a 94% favorite.
Final
 Purdue Boilermakers | 30 |
|---|---|
 Notre Dame Fighting Irish | 56 |
Replay with same day's form
Luck index 0 Notre Dame about even · 0 Purdue
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. Purdue wins 0, Notre Dame wins 10.
- 1 PUR 51 ND 72
- 2 PUR 31 ND 61
- 3 PUR 37 ND 73
- 4 PUR 14 ND 54
- 5 PUR 14 ND 59
- 6 PUR 17 ND 65
- 7 PUR 20 ND 72
- 8 PUR 10 ND 66
- 9 PUR 23 ND 84
- 10 PUR 0 ND 70
Three other ways to ask
Each answers a different question, so none of them replaces the replay above.
Before kickoff
The closing betting line, turned into a probability. What everyone knew before the game.
Same teams, fresh 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.
Only coin-flips re-rolled
Every kick, fumble bounce, conversion and judgment call redrawn; everything else fixed. The narrowest view of luck.
How 4,000 replays ended
Purdue wins 0% of them, Notre Dame 100%. The line is what actually happened: Notre Dame by 26.
Show as a table
| Final margin in the replays | Share of replays |
|---|---|
| Purdue by 17+ | 0.0% |
| Purdue by 9–16 | 0.0% |
| Purdue by 1–8 | 0.1% |
| Level after regulation | 0.0% |
| Notre Dame by 1–8 | 0.5% |
| Notre Dame by 9–16 | 1.4% |
| Notre Dame by 17+ | 98.0% |
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.
The kicks
How likely each kicker was to make that kick (his own record, the distance), and what happened.
- S. Porath, 48 yds made · 56% expected
- S. Porath, 26 yds made · 89% expected
- S. Porath, 35 yds made · 79% expected
- E. Schmidt, 31 yds missed · 85% expected
Penalties: Purdue 5 for 45 yards, Notre Dame 3 for 30 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
| When | Flag | Win probability for |
|---|---|---|
| Q1 14:23 | Unsportsmanlike Conduct on Purdue, 15 yards | +2% ND +3.2 pts |
| Q1 11:22 | False Start on Purdue, 5 yards · pre-snap | 0% ND +0.6 pts |
| Q1 4:41 | Holding on Purdue, 10 yards, wiping out the play | +1% ND +2.2 pts |
| Q2 12:07 | False Start on Notre Dame, 5 yards · pre-snap | 0% PUR +0.7 pts |
| Q3 6:15 | Holding on Notre Dame, 10 yards, wiping out the play | 0% PUR +1.3 pts |
| Q3 1:58 | Holding on Purdue, 10 yards | 0% ND +1.3 pts |
| Q4 3:27 | Unnecessary Roughness on Notre Dame, 15 yards | 0% PUR +1.2 pts |
| Q4 2:59 | False Start on Purdue, 5 yards · pre-snap | 0% ND +0.6 pts |
When it happened
Notre Dame’s chance of winning
Numbers mark the biggest luck moments, listed below.
| # | When | What happened | Win probability for | Next drive |
|---|---|---|---|---|
| 1 | Q1 14:23 | Unsportsmanlike Conduct on Purdue, 15 yardsJudgment calls | +2% ND | ND: Touchdown |
| 2 | Q1 12:17 | Purdue converted 3rd & 43rd & 4th downs · 47% expected | +1% PUR | PUR: Touchdown |
| 3 | Q1 9:34 | Notre Dame converted 3rd & 33rd & 4th downs · 62% expected | +1% ND | ND: Touchdown |
| 4 | Q1 7:38 | Notre Dame converted 3rd & 63rd & 4th downs · 46% expected | +1% ND | ND: Touchdown |
| 5 | Q1 4:41 | Holding on Purdue, 10 yards, wiping out the playJudgment calls | +1% ND | ND: Touchdown |
| 6 | Q1 3:59 | Purdue fumbled and recovered itFumble bounces · loose balls are close to 50/50 | +0% PUR | PUR: Field goal |
| 7 | Q1 3:00 | Purdue converted 4th & 53rd & 4th downs · 41% expected | +1% PUR | PUR: Field goal |
| 8 | Q1 1:00 | Purdue converted 3rd & 113rd & 4th downs · 25% expected | +2% PUR | PUR: Field goal |
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
Purdue 0% · Notre Dame 100%
- Final margin
- Notre Dame by 26
- Luck in points
- 12.9 for Purdue
- Luck-adjusted margin
- Notre Dame by 38.9
- Replay with same day's form
- Purdue 0% · Notre Dame 100% unchanged: why
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 · 
Purdue · 
Notre Dame
More from Week 4 2025
- Ball State at UConn CONN 31–25 · replay 37% for the winner
- Michigan at Nebraska MICH 30–27 · replay 39% for the winner
- Iowa at Rutgers IOWA 38–28 · replay 80% for the winner
- Washington at Washington State WASH 59–24 · replay 80% for the winner
- Maryland at Wisconsin MD 27–10 · replay 80% for the winner
- Michigan State at USC USC 45–31 · replay 89% for the winner
- Oregon State at Oregon ORE 41–7 · replay 100% for the winner
- Illinois at Indiana IU 63–10 · replay 100% for the winner
- Fresno State at Hawai'i FRES 23–21 · replay 24% for the winner
- Troy at Buffalo TROY 21–17 · replay 30% for the winner
- Arkansas at Memphis MEM 32–31 · replay 30% for the winner
- Syracuse at Clemson SYR 34–21 · replay 34% for the winner