Wang is going to be a free agent after the 2010 season so to keep him the Yankees are going to have to pay him elite dollars over a long-term to stay: He will likely have a case that he should be paid commensurate with the five years at $82.5 million bestowed A.J. Burnett. And the Yanks, internally, are not positive about going to such extents with Wang. He has pitched four seasons in the majors and two have been interrupted by injury. They wonder how a pitcher who does not strike out batters will age as he loses some bite on his sinking fastball, especially since he has been sketchy in developing the rest of his repertoire. And he would begin a new contract in 2011 at age 31, so you almost certainly are buying declining years.
Because of all of this, the Yankees have weighed trade scenarios in the past involving Wang and, I suspect, they will continue to at least listen, especially if they believe that Hughes is capable of being, at minimum, a cost-effective, mid-rotation starter. The Yankee logic would be simple: If they do not think they can go long-term with Wang then would they be better off letting him pitch for them through 2010 or to use him to potentially fill another area of need via trade? Remember, the Yanks might be hoping to further stock the top of their rotation with someone they would rather invest the money in than Wang such as a trade for a Roy Halladay or an international signing of Yu Darvish.
It'll be a sticky situation when Wang gets close to free agency. The Yanks have plenty of higher ceiling pitchers in the minors, and I'm sure there will be some available via trade and free agency.
Wang has certainly won his share of games, but his incredibly low strikeout rate means it might be tough to maintain effectiveness as he loses his 'stuff'.