Better game times, more press coverage, etc. There's likely no evidence that was EVER the case, but I was told that by someone who worked for PIHL a few years ago.
And yes, not taking into account graduating classes from the year before is an issue (I've been there, believe me). This is where school enrollment, program enrollment, and 5-10 year history should be taken into consideration like Rewster said above. It would provide a good idea of how quickly a program can bounce back.
The attitude of "there is no benefit of moving up, ever" though is why the classifications are sized the way they are currently.