I'm prepared to be proven wrong, but I saw a Tweet saying Happ's price was too high for some clubs, and if we can't get him for something approximating a bag of balls, I'd be surprised if Theo made the move.
Rosenthal already pointed out, too, that the Yankees apparently have so much prospect depth that without some deals like this, they were going to have to expose some guys to the Rule 5 draft that they didn't want to.