Let me explain something - big lumbering white guys are incapable of becoming good NBA centers. Chris Kaman? Huh? Slow. Weak defender. Zero shot-blocking ability. Very limited offensive game - and yet, he is somehow considered a top young Center.
On the other hand, at age 36, Alonzo Mourning is proving for the second straight year in Shaq's absence that he is still a top 5 NBA center. While his offensive game definitely disappeared, Zo remains the best shot blocker, and one of the premier interior defensive presences in the game. With Shaq out, who is better? Yao, Dwight Howard, maybe Okafor, a recovering Amare and probably Ben Wallace.