There is only roughly 150 professional Rugby contracts in Australia. I think the percentage that come from the GPS is really high if you look at like an industry.
If you look at the Australian Schools/U18s it’s considered a good cohort if 5-6 of the squad end up having a meaningful Rugby career of 5+ years. That probably means only 1-2 might be Sydney GPS players. Heaps of reason for this and most come to physical development stages and a number of them were advanced while at school but didn’t continue. It’s no different to any career. As you go higher the pool just gets smaller. Even the best school boy will top out at some point.
I was watching the Roosters v Parramatta game on Friday and there were 5 Sydney GPS boys in that game alone: Chrichton, Smith, Sua’ali’i, Pennisini & Simonsen.
Between the NSW & QLD GPS the production of professional footballers is exceptional.
In regards to players not playing after school, I think it would disappoint to know how many will stop after a year or two of Colts. This is unfortunately the standard through all Club Rugby at the moment and not just the GPS players. Contact sports are becoming more niche and I generally think people can’t be bothered if there is nothing to be gained i.e a pro contract.