No way in hell is Yao anywhere near even the top 15 offensive centers of all time. I could easily name 15 I'd rather have. Yao was a slow and terrible player. He hurt the Rockets when he played with McGrady in my opinion. I felt they were a much better team with Yao off the floor. No way in hell is he a top 5-6 center.
Yao had maybe the most diverse offensive skillset of any center, as he could play in the post, take complete advantage of his size, and step out and hit the three, but I am not sure he was as offensively aggressive and willing to put his team on his shoulders like Shaq, Kareem, Ewing, Wilt, Hakeen, etc. could and did.