K&U is proceeding from a false premise. Barry has played centre half, left back and left midfield for Villa but is not, and never has been, a central midfielder.
I think that the "natural left sided" qualification is an important one. Throughout Sven's reign, the left side of midfield was unbalanced by virtue of the fact that we lacked a left-footed midfielder of sufficient standard. Playing right-footed midfielders (with the possible exception of Joe Cole) meant that they were predictable (because in order to cross the ball they would have to come inside) and reduced Ashley Cole's effectiveness on the overlap. If Giggs was English, he'd have held down the position for years and that sort of flair is what we have been lacking. Barry isn't the fastest, but he can beat men and puts in a good cross. He also has a versatility which makes him ideal for tournament squads.