Have you really just compared Kucherov and Rubtsov?
Kucherov was the best prospect of 2-3 birth years. Maybe Kucherov would be an even better player now if he stayed in Russia for another year or two,
but we'll never know. But comparing him to a prospect never projected to be at least among the top3 in his age group is silly. Those ususally take much longer to develop and need more caution. And caution is what goes overboard when they start jumping to NA and back at this age. 99% of them become worse players afterwards. Ask Kucherov's former linemate and a guy picked much higher at the draft Grigorenko.