I'd think about this question in the context of Ben Wallace. Figure that a pro wrestler isn't likely to have any particular skill for putting the ball through the hoop. Big Ben is a bit of an anomoly in the League, in that he was able to carve out a niche for himself with zero offensive talent but the ability to be a game-changer on D.
Why was he successful? Wasn't because he was tall. Wasn't just because he was strong. It was his quickness and athleticism that let him overcome the fact that... well, he's just not very good at playing basketball.
Think, too, of Stephen Neal on the Patriots. He was able to become a pretty [dang] good interior lineman without having player football in college. As a "real" wrestler, though, he has to have incredibly good footwork, which I'll argue is one of the key elements to making him BE a success in the NFL (in addition to have great strength and balance).
You don't think of pro wrestlers as necessarily having great footwork. If you don't have a lot of natural basketball talent, I'll argue that you need to have that footwork and quickness; if you've got it, you might be able to become a solid defensive player and rebounder.
So, I'll argue that someone like a Stephen Neal - a very good collegiate wrestler - could become a good defensive NBA big man *if* they were sufficiently tall. Height alone isn't enough, strength alone isn't enough.
Oh, and yeah... there's that little issue of PEDs to overcome...