i dont think that Dwight is the problem, it is the fact that Steve Nash can not play defense to save his life and they are not running a uptempo run and shoot offense, so Nash also cant play the half court triangle sets or isolation either.
there is a lot of good young point guards and combo guards in the NBA now, with tons of potential. And they are going to eat Nash up every game. (Collison and Lillard for example.) Guys like Kyrie Irving are going to shit on the Lakers for this very reason. Russel Westbrook is going to eat them up and spit them out