Like I said in another thread Kampmann and Ellenberger are more dangerous fights for GSP because they have more tools. I don't really think it is fair to compare Hendricks to the guys you are comparing him to though he is a better wrestler than all of them but Kos and he trashed Kos standing when he wasn't being eye gouged.
Kampmann's head movement is fine. He is good at slipping punches; it is his footwork that is terrible.
GSP didn't tool Kos the second time around or Shields wrestling and Fitch got tooled wrestling by BJ so I don't think you can act as though he is some amazing wrestler. Guys like Ellenberger and Hendricks should be able to stop most of his takedowns.
To be fair, GSP didn't try to tool either one at wrestling. He wanted to stand with them. The fact that he was able to stop THEIR wrestling, which is their primary weapon which was something they've used against several other high level fighters means GSP DID control the wrestling.
Fitch is an amazing wrestler. Just because he got taken down by BJ doesn't change that. That was a shock factor, not a weakness. Ellenberger and Hendricks will have nothing for GSP in the wrestling department. Nor will anyone at 170 right now.