Yes that is one aspect of the decision making process. It is not the most important, in fact I would think that a high performer (no not just an athlete) will have just an easy of a time finding a worthy mate in Stanford as in Provo.

My argument is the same as I make when discussing BYU and Stanford academically. I think that if you put the best of the best at BYU against those at Stanford you would find them to be on par with one an another. But it is with everyone else that the Stanford student body exceeds that of BYU. The same could be said for the YSA environment sure the pool is smaller but that does not mean it is not as good, in fact I would say that on average they are much better than the average at BYU. So if pure numbers is what you are looking for yes Provo and Orem is the way to go. If quality is what you are after, maybe you need to expand you criteria and your views.