I agree with your point that in order for the Rockets to be TRUE contenders (and not media-hyped contenders), Yao MUST be at the top of his game ALL the time. He can take some games off in the season as long as we get into the playoffs, but once there, he can't do like last year and not show up. T-Mac AND Yao (not either/or) must both be capable of consistently playing at a high-level when it matters. T-Mac has proven he can do that (he averaged nearly 40 pts a game in one playoff series a few years ago), so no worries as far as he is concerned. For Yao, however, the jury is still out, although I think he will more dominant in the playoffs this year. Even players like Sura and Barry and Wesley, they too must be at the top of their games (most importantly making their open shots) if the Rockets are to at least compete against the better teams in the playoffs. Still guys, this team is not really built to win NOW, because to do so it means that both our star players must be near the prime of their careers, which is clearly not the case. That is why comparisons of T-Mac/Yao vs. Shaq/Kobe are simply rediculous, since while you can make a case for the T-Mac/Kobe comparo, you can't compare Yao vs. Shaq. But when Yao gets there as a dominant force with more experience under his built, then you can start comparing the two dynamic duos.
Mac is the established superstar on this team. He needs to be the one getting the ball in crunch time and often. Yao is a 3rd year player who makes a great second option until he matures and can dominate consistently