The Sports Network has a story out of Ivy League football media day suggesting that with Harvard, Penn and Brown the dominant teams of the recent past, "(t)he disparity has forced Columbia, Cornell, Dartmouth, Princeton and Yale into head coaching changes in recent seasons to try to close the gap on the Big Three."
Some of the reason for changes have been a little more nuanced than that might suggest but you get the idea.
For a look at what each school had to say after media day, click on these direct links to stories from the schools. (Princeton didn't have one that I could find.):