My theory is that he’s trying too hard. He is the athletic focal point of an entire nation and all they expect is a perfect game when he pitches. He also is feeling the heat of being the ace on a team that includes Roger Clemens, Mike Mussina and Andy Pettitte.
That emotion is reflected in how poorly he has pitched with men on base.
He also lost his best friend when Mike Myers was released. Myers was the guy who would prod Wang to go out and get dinner instead of having room service. They also worked out together before games.