If you add 'unexpectedly' to BigSlick's original question, I think you could go back to Edmonds. All the young guys were fun their first 50 ABs, but in a vacuum none of their successes were all that surprising. Edmonds was cooked and what he did was so out of left field; Bote wasn't considered a major prospect so what he's doing has been a nice bonus.
It was, but if Chatwood wasn't terrible he wouldn't create high-leverage situations where a reliever was needed in the fifth freaking inning every start.
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.