This is a good thread.
For me there are a confluence of reasons why we climbed almost to the top of the pile, and similarly more than one reason why we are in decline now. Most of those have already been covered.
To add to the discussion I would also add that Poch did not learn one of SAFs greatest lessons. That is that coaching team needs to be refreshed periodically too. You can buy into a coaching philosophy for so long but it looses it's power over you after a while. You need fresh voices and/or fresh ears and we had neither.
Our failure to win something, even a smaller trophy, compounded the other problems. Winning anything changes the mindset and would have prolonged our time at the sharp end, IMO.