This is the best quote I can find regard for Wang's outing from MLB beat Writer Bryan Hoch who response a Yankees fan's worry on his blog(Bombers Beat),
We'll try to find out more later but his command was really off. Seemed like the hits were up and everything else was skidding in the dirt.See, game was played on March 6th which is Wang's second start, so his command should be off as expected. The same situation should goes to Kennedy and Joba's cases as well.
Updated: Peter also pointed out today, Wang and pitching coach Dave Eiland figure out it was mechanics flaw. By the way, Wang told Taiwanese media, He threw very good changeup and splitter while his sinker and slider were flat.