Perkins is an excellent team defender, VERY aware of what the whole offense is doing, and of controlling the lane, not just defending his man. He does benefit from having a strong defender at pf who is mobile, like KG, but he also amplifies such a defender.
And yes, we need to keep front and center the fact that we are constantly talking about how desperately we need bigs, when WE HAD ONE OF THE BEST DEFENSIVE BIGS is nothing short of an insane situation to be in, thanks to Danny's manic episode.