Yao Ming's career is a what-if question.
The biggest what if Yao is afraid to answer is where he would fit in the current NBA.
Shaquille O'Neal is famous for lamenting the end of the traditional center. Yao is too as he looks at the landscape of the current NBA. And since Yao would be playing if not for chronic foot injuries that ended his career in 2011, he really knows his place in the NBA was getting squeezed out.
Yao told Karan Madhok of SLAM that he feels he would not be successful in today's NBA because of his poor mobility and his inability to create free throws, in his words:
I’ve thought more than once about how I would compete in today’s basketball if I was still healthy and in my best shape. I think, if you can make enough free throws, or create enough free throws, you can still be effective. Otherwise, you probably need to run with the small ball. Someone like Shaquille O’Neal could create enough free throws for himself. He was very dominant and could change the pace of the game with that. But, the shooting skill today is so incredible. The three-pointer is so easy today. I think they should extend the line even another meter farther [laughs]. The defense is much more stressed by the range. And obviously, players with size like me would find it much more difficult to guard a shooter. So…[today’s NBA] definitely would not be easy for me.
Yao Ming is not one for regrets. He says so in the interview with Madhok. It does not seem like he feels like he did anything more than he was supposed to do in the league and his teams went as far as he and his teammates could take them (which is kind of depressing considering how special Yao was before the foot injuries knocked him out).
Certainly in this NBA with more mobile centers and big men, a lumbering giant like Yao would have his struggles. Teams would have to adjust to him, and it is near impossible to defend a 7-foot-6 jump shooter.