It's not his post defense against Howard that is a concern, it's him having to come out of his comfort zone which OKC is going to make him do everytime Nash is in the game.
That's a valid point. Nash is pretty much conceding Rose wherever he wants to go, so Al, Deng, and Smith will constantly be in a state of help defense.
How have teams that have beaten Chicago deal with this when their point was so woefully equipped?
Jose Calderon is a pretty terrible defender, right? And Andrea Bargnani isn't exactly an intimidating low-post defender, correct?
Despite this, Calderon is 6-2 against Rose.
You do this by limiting Rose with good help defenders, like Amir Johnson, and exploiting other mismatches.
Also, didn't fitz say that he'll hide Nash on Iman Shumpert or Chase Budinger, using Gordon / Deng to pick up Rose?