What I like about having Fitz and Williams outside, is that it puts a 6'5" down field target across the field from our biggest play maker. That would really put pressure on defenses as far as bracketing Fitz. Add Breaston in the slot, who could be used to push the seam route, pulling safety coverage back and opening up the deep-in route for Fitz, and this could be a tough group to cover.
Now we have to consider that Williams is pretty raw still, but with his size, skill, and relationship with DA, he may bring more of an impact to the passing game than either Breaston or Doucet as a 2nd or 3rd receiving option.