How do you know there was no interest? And given the age in their rotation and relative lack of other viable starting options in the system, why would the Yankees want to move him now? He's a valuable (and cheap) piece and a solid number 3 or 4 starter. Unless they could get a comparable proven young starter in return, it doesn't make sense to me.
Actually I have heard there is interest. He's eligible for free agency after this year and teams will look to offer. The back ailment may actually play into the Yankees hands with respect to what he can expect in terms of a Contract.