Defense when Yao's in the game

Do we always play a zone when Yao Ming's in the game?

It seems to me as if Yao's expected to pretty much cover the middle. He's above the lane, he's down near the basket ... he's pretty much roaming the middle. But too often he gets caught too high guarding someone he shouldn't, and they take him off the dribble, knowing there's no other center protecting the goal.

You guys notice this at all, and have any comments about our defense when Yao's in the game?

Not completely related, but ever since Mo came back, I've also noticed we've gone to Yao, Mo & 3 guards in the 2nd and 4th quarter (particularly vs. the Lakers). Why not Yao, Mo & Eddie Griffin? Was this because we were matching up with a Shaq-less Laker team, or are we to expect more of this small ball with a giant and a post player from the Rockets? I really wanted to see Yao, Mo, EG, Cat & Franchise out there at the same time. If EG were out there as well, I don't think we'd see Yao getting stuck on a guard (on defense) quite so often.

 

Okay, fair enough. Admittedly, I didn't get to watch the Phoenix game. But regardless, the point of the comment wasn't the time he was inserted into the lineup as much as the lineup itself. Why Yao, Mo and 3 guards?