I think positions in general are overrated. It is about talent and ability. Although size is a big part of that.
What I think you will find is that success is not dictated by a certain position. Instead, it is driven by great players on balanced rosters...and most great players have good to great size for their positions.
Lebron, Kobe, KG, Duncan, Jordan, Hakeem, Bird, Magic.
All of these guys were at least ideal size, if not big for their positions. It didn't matter what position they played, just that they were the best player on the court and able to dominate the players forced to cover them.