Around 2007, Yao was a consistent 22-10 star player, attracted double team regularly. In one period, he was on the 25/12 pace, in serious talk of MVP racing. In 2003, he was a public figure with good size and hands, who had a decent jump shot.
I don't know what skill set you were talking about that he diminished in those years of hard working. The array of offensive moves and dominance he showed in the low post were eye poping. He was caught on camera, taunting Chris Karman, "You can't fxxking stop me". That's how confident he was. That's how good he was, AFTER all those years working on his skills and strength.