That's not what most talent evaluators say, including John Sickels, whose link was posted earlier on the thread.
Most people doing this rankings say that the Red Sox farm is loaded with high-upside talent, but that it will take time for them to make an impact. It has been repeated over and over in the thread that for any given year, evaluators grade both talent and potential impact on the MLB club. The "talent" part of the equation is not the knock on the farm system. You have a pre-conceived notion on this subject that is honestly not correct.
You can repeat it 'till you're blue in the face, but i'm going to trust the evaluators on this one.
Also, the "other GM's aren't going to give away an SP" point is irrelevant to the quality of the prospects. A GM can ask for the moon for a serviceable pitcher like Gavin Floyd, and he won't get it. That's not a knock on the farm systems of the teams that end up not acquiring him, but rather a problem with the GM's expectations.