This is absolutely an oversimplification and hopefully nobody is taking it as the be-all, end-all. I tried to make it clear that there are other factors and this is just a simplified version. But I do think it's a useful starting point.
That said, I'm not sure I see the value of large alumni bases.
If you have alumni that aren't watching games (TV viewership) or going to games (game attendance) or in the local area (market size)... then I'm not sure those are incredibly relevant.
A place like Cal has a ton of alumni - well over half a million. But they don't support or attend or watch football, so it doesn't matter.
UCF has a large undergrad enrollment, but small alumni base. But the bigger factor was that they represented a top 20 TV market in the US... I think market size (Houston, Orlando, LA, Texas, Maryland, Rutgers in New York) has been more the driving factor than alumni size