The two pitchers were both signed to long term under market deals. They absolutely could have kept them for a long time.
They chose to sell off extremely valuable assets rather than try to compete. It follows that they got back good prospects.
So good job breaking up a young core of cheaply signed major league assets in a somewhat efficient manner? Yay?
Yeah, while Heyward and Upton had a year of control each, Sale and Eaton were signed to longer-term, team-friendly deals. Their return for Eaton isn't looking so good at the moment.