It's not about waiting for them to develop. You have repeatedly said the Sox gave up "garbage" in their trades.
Now if Yoan Moncada (97OPS+ in 549PA at 23 years old) and Manny Margot (OPS+ 86 in 885PA at 23 years old) were performing similarly on the Sox, would you recommend they be replaced? If so, you'd hardly be the only fan.
But on the other hand, both players are only 23 and don't have much experience.
Not to mention most of the payers the Sox have dealt away have not even reached the majors yet, including Kopech, Dubon, Basabe, Espinoza, Guerra, etc.).
I think calling them garbage is a bit premature. They might be that way, but not yet...