If it was only about the money, the Sox would have traded him to Texas and given up the entire contract.
There is a good chance you’re (deliberately?) overstating Atlanta’s interest. They did insist Boston include money if Boston wanted anything of potential value in return. If they were, as you say, VERY interested, that feels like a demand that could jeopardize the deal.
I mean, Boston had a 35yo oft-injured pitcher who had posted less fWAR over the previous 5 seasons than Martin Pérez. They traded him clearly not solely to move the money, but also tried to get something of value back. Would you prefer management that just unloaded contracts without trying to get back players and saved more money? Do you prefer management that clings to non-performing veteran talent and keeps their salaries on the books so as not to pave the way for other players?
It really seems like you do…