On campus, a successful football team is a cause for celebration.

So much celebration, in fact, that three economists have found a link between a winning season at one big-time football program and lower grades for male students.

In a new paper, the economists at the University of Oregon chart the grade point averages of students there alongside the fortunes of the football team between 1999 and 2007. Their findings could give ammo to critics of big-time college sports.

Their conclusion: When the Ducks were winning, students celebrated more and grades suffered.

Women's grades held up better than men's when the team was doing well — and the drop in men's grades compounded a GPA gender gap that was already present at Oregon, as it is on many campuses.

The bottom line: Three extra wins for the Ducks' football squad in any given year caused a drop in male GPAs that's about as steep as the one you'd expect if male students had scored 27 points lower on their SATs.