They played 2 guys at Center each about 20 mpg. Jonathan Tchamwa Tchatchoua was a dominant defender and strong rebounder. Mark Vital was a bull that was difficult to handle. If you combine those 2 guys they got 12 ppg and 12 rbg while player very strong defense.
Of course we know they were led by strong bodied guards and a lot of them. They didn't need a big man to be a dominant force. They were just lucky enough to have 2 guys that brought different things which combined, equaled a pretty dominant big man.
I don't think you need a dominant big man to win. That said, if you do have one, it makes it much easier. That's why they are in such high demand.