I can't find them now, but I remember someone posting lists of the first year stats of the top 50 recruits over a 3 year period (a few years back). In general:
The Top 15 Recruits did fairly well in the first year, with a few flops.
But from 16-50, it was very much hit or miss. Many did OK in limited minutes. There was some that were very good right away, but it was very limited amount. Some did nothing.
I think this board generally usually aims too high in what it predicts / expects from frosh. Some hit, the majority do not. And its not unique - I suspect most fanbases do the exact same, especially those that are middling a bit.