That's the way the game is played.
A bird in hand is worth 2 in the bush, but it the open market of MLB baseball a high end talent like crochet is worth 3 birds in the bush.
If all the prospects pan out, or even just two hit their ceiling it's going to look like the Sox got fleeced. But for a point of reference in Yoan Moncada, Luis Basabe and Michael Kopech all hit their ceiling that would have looked like an awful trade on our part, but in the end you don't complain if the guy you got does what he's supposed to do.
In a fair trade, it hurts both sides, both sides have to feel like they're winning the trade.