Certainly, Bishop England's statewide stranglehold on Class AA athletics in many sports bespeaks the advantages of its wide enrollment area and (ahem) occasional "recruitment" of athletes. In boys' soccer, it also speaks volumes of the relationship between DISA and BE.
This is not to downplay the importance of coaching, tradition, etc. It just is what it is, and don't think for a minute that public school Class AA coaches don't question it all the time.
Because then, you'd be wrong! (Just kidding. I like the tag.)