Jolly drafted at 19 years old,ditto Cox & Sandi. The others all drafted in early 20's apart from Stephenson who is probably 3rd in line at best for Geelong.
Not saying you can't draft a good ruckman from state leagues but most of them are playing at that level for a reason
i think because so few ruckmen are available each draft most of them end up on a list one way or another.
look at this draft theres only probably 3 maybe 4 ruckmen close to 200cm who will be taken in the top 60 odd. from there watch how many get rookied.
i think so many good ruckmen are found in the rookie draft because the majority are taken there ot very late in the nd.. not a lot end up in state leagues unaligned to a afl club.. only a theory and i could be totally wrong.