I think many of those populations are skewed...
Great Oak has a population of 3100+ this year. Feel free to call the school to get an accurate count, as clearly the media isn't doing that and is misrepresenting our numbers this year (Milesplit NY).
For any school allowed to use middle school athletes, those populations must be added to their population totals as well (any grade that is eligible from any school that feeds into the high school).
This makes Great Oak ~3100-2100 to Manlius from what I can tell. Still a population advantage, but certainly not the chasm some of these morons are reporting.
We are talking about coming up with 5 athletes, so any population of over 1000 has a decent chance to do that regularly. When you get populations over 2000 and 3000 then you see an advantage particularly in year to year consistency because there are lots of athletes to fill in the gaps from year to year.
Sometimes the bigger schools offer more sports as well. We have opened Mountain Biking, Rugby, Field Hockey, Lacrosse, Boys Volleyball, etc. which make it harder to get kids out. Also our district has forced JV reserve teams on us. We have Varsity, JV, JV Reserve, and Frosh for Volleyball, soccer, etc. for girls which has taken a lot of potential athletes out of the XC/Track pool as well. How many athletes are on the campus doesn't tell the whole story, but is an advantage by its nature.
One of the things that seemed pretty clear at the clinic was that the majority of top teams were dealing with mid to upper middle class athletes from educated families almost across the board. It would be interesting to see a study outlining school population wealth (income, housing prices, etc.) as a determining factor for success at NXN.