This.
The only Sox prospects with real value are the ones you don't want to trade. (Robert, Madrigal, Vaughn, Kopech) Unfortunately, all of the secondary guys that we hoped would supplement the team via trade, haven't panned out to be much of anything. They're all bordering on non-prospect status rather than having any sort of trade value.
You can count the number of actual prospects in the Sox system on two hands.
JMO: the Big 4 and Matt Thompson/Dalquist are about as deep as the Sox system goes.