I don't think anyone has suggested a player based on what their 'potential' is. All mentioned have both produced and have talent to varying degrees. Yes, Mcknight has produced and he IS talented, but he's not exactly a threat to any defense. In the clutch I would rather the ball be thrown to McCoy, Hackett, or Carruth. They we're all more of a deep threat (helping to stretch the field, opening up other parts of the game), could block down field, and we're better gaining yards after the catch.
Its not a knock on Scotty, I just think the those 3 were better all-around WR's.