They have Westbrook, not Harden, his D is fine. George is an above average defender, especially for a guy who carries a big load at the other end. Melo is not a good defender but guarding 4s should help him some and also position him to get more boards. They still have Roberson and some other good defenders. I guess they did lose some D between Gibson, mini-Sabas and Oladipo, but they sure didn't lose much with Kanter.
I see their roster being incomplete and mish-mashed but then again they have two guys who can play huge minutes and still have some pluggers like Adams inside.
The more salient critique to me is that they made all these moves and could still lose in the first round. I see them as like a 4-ish seed that could quite possibly be able to get to the second round and lose there.
And you will know MY JACKET IS GOLD when I lay my vengeance upon thee.