Week 2 2025 · September 6, 2025
Southern Illinois at Purdue, Week 2 2025: who deserved to win?
Purdue beat Southern Illinois 34–17, and the replays back it up: with the way both teams actually played, Purdue wins 9 of 10.
Before kickoff Purdue was a 93% favorite.
Final
 Southern Illinois Salukis | 17 |
|---|---|
 Purdue Boilermakers | 34 |
Replay with same day's form
Luck index +7 Purdue about even · −7 Southern Illinois
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. Southern Illinois wins 1, Purdue wins 9.
- 1 SIU 17 PUR 10
- 2 SIU 21 PUR 24
- 3 SIU 21 PUR 28
- 4 SIU 14 PUR 24
- 5 SIU 3 PUR 17
- 6 SIU 7 PUR 24
- 7 SIU 3 PUR 23
- 8 SIU 7 PUR 31
- 9 SIU 7 PUR 34
- 10 SIU 7 PUR 45
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
Southern Illinois wins 7% of them, Purdue 93%, counting the 1% still level after regulation as half each. The line is what actually happened: Purdue by 17.
Show as a table
| Final margin in the replays | Share of replays |
|---|---|
| Southern Illinois by 17+ | 0.5% |
| Southern Illinois by 9–16 | 1.5% |
| Southern Illinois by 1–8 | 4.4% |
| Level after regulation | 1.2% |
| Purdue by 1–8 | 18.0% |
| Purdue by 9–16 | 18.8% |
| Purdue by 17+ | 55.6% |
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, 25 yds made · 88% expected
- P. Geelen, 59 yds missed · 39% expected
- S. Porath, 43 yds made · 64% expected
- P. Geelen, 53 yds made · 47% expected
Penalties: Southern Illinois 5 for 66 yards, Purdue 2 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 7:02 | Pass Interference on Southern Illinois, 12 yards | +2% PUR +2.0 pts |
| Q1 1:40 | Roughing the Passer on Southern Illinois, 15 yards | +2% PUR +1.8 pts |
| Q2 13:36 | Pass Interference on Southern Illinois, 15 yards | 0% PUR +0.6 pts |
| Q2 2:41 | Personal Foul on Southern Illinois, 9 yards | +1% PUR +1.3 pts |
| Q3 4:54 | Block Below the Waist on Southern Illinois, 15 yards | +1% PUR +1.4 pts |
| Q4 10:30 | Personal Foul on Purdue, 15 yards | 0% SIU +1.6 pts |
| Q4 10:16 | Roughing the Passer on Purdue, 15 yards | 0% SIU +1.6 pts |
When it happened
Purdue’s chance of winning
Numbers mark the biggest luck moments, listed below.
| # | When | What happened | Win probability for | Next drive |
|---|---|---|---|---|
| 1 | Q1 14:05 | Southern Illinois converted 3rd & 93rd & 4th downs · 33% expected | +2% SIU | SIU: Touchdown |
| 2 | Q1 7:02 | Pass Interference on Southern Illinois, 12 yardsJudgment calls | +2% PUR | PUR: Touchdown |
| 3 | Q1 3:07 | Purdue converted 3rd & 43rd & 4th downs · 49% expected | +2% PUR | PUR: Touchdown |
| 4 | Q1 1:40 | Roughing the Passer on Southern Illinois, 15 yardsJudgment calls | +2% PUR | PUR: Touchdown |
| 5 | Q1 0:00 | Southern Illinois was stopped on 3rd & 13rd & 4th downs · 80% expected | +2% PUR | SIU: Punt |
| 6 | Q2 6:59 | Southern Illinois was stopped on 3rd & 13rd & 4th downs · 80% expected | +2% PUR | SIU: Turnover on downs |
| 7 | Q2 6:21 | Southern Illinois was stopped on 4th & 23rd & 4th downs · 66% expected | +3% PUR | SIU: Missed field goal |
| 8 | Q2 3:36 | Purdue converted 4th & 33rd & 4th downs · 55% expected | +2% PUR | PUR: Touchdown |
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
Southern Illinois 2% · Purdue 98%
- Final margin
- Purdue by 17
- Luck in points
- 5.0 for Purdue
- Luck-adjusted margin
- Purdue by 12.0
- Replay with same day's form
- Southern Illinois 7% · Purdue 93% 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 2 2025 games · 
Southern Illinois · 
Purdue
More from Week 2 2025
- Boston College at Michigan State MSU 42–40 · replay 8% for the winner
- Miami (OH) at Rutgers RUTG 45–17 · replay 46% for the winner
- Illinois at Duke ILL 45–19 · replay 47% for the winner
- Iowa at Iowa State ISU 16–13 · replay 52% for the winner
- UCLA at UNLV UNLV 30–23 · replay 64% for the winner
- Western Illinois at Northwestern NU 42–7 · replay 80% for the winner
- Michigan at Oklahoma OU 24–13 · replay 84% for the winner
- Northern Illinois at Maryland MD 20–9 · replay 93% for the winner
- Florida International at Penn State PSU 34–0 · replay 99% for the winner
- Kennesaw State at Indiana IU 56–9 · replay 99% for the winner
- Northern Iowa at Wyoming WYO 31–7 · replay 99% for the winner
- Middle Tennessee at Wisconsin WIS 42–10 · replay 99% for the winner