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.
Perhaps dominant is too strong of a word, but you definitely need a big man with the ability to control the paint defensively, and provide offensive production from the post when the shots aren’t falling.
Baylor’s team could certainly muck up the paint, but they had so many great shooters, they rarely had to rely on their bigs for offense. My posit is more of a generality, than a natural law. There are occasional exceptions, but I would argue that Baylor could score from the post via Mark Vital, at a pretty good clip. He might not have been a traditional dominant big, but he created a lot of mismatches.