If Preston Wilson is traded, his value will go down. Period. Trading for him isn't neccesarily bad, but he won't be in a better situation, so unless the P-Dub owner in your league fears a trade then you'll probably be paying too much. In one of my leagues, he was just traded for Chipper Jones. That seems like a fair trade to me, even though Chipper has been slumping, since his value is on the rise, and Preston's is presumably on the decline. He was traded for Mark Buehrle in another league. If his owner is that desperate in your league, by all means trade for him.
"Jack, will you call me, if you're able?"
"I've got your phone number written, in the back of my Bible."