Whether or not JVG could wrest fifty wins out of this team is unanswerable, but based on his historically mediocre offensive teams I question if his ability to teach defense would make up for his deficits at this end of the court. Furthermore, this team already runs its offense through Roy and LaMarcus no? And correct me if I'm mistaken, they've somehow manged to have a top 3 rated offense all season long, so he must have them doing something right at that end of the court.
On the defensive end I tend to attribute the defensive struggles early in the season not so much to any systemic problem with schemes or coaching, but rather with the overall youth and inexperience of the team -- as the season has progressed they've become more cohesive, more used to playing with one another and presumably their ability to read and react correctly on defense has improved with repetition. Isn't it possible the Blazers are finally playing defense the way Nate wants them to?
As I said before you don't have to be a Nate believer or like him, but to not give him any respect for the job he has done seems a little 'strange' (for lack of a better word).