It's not just "smart like Werdum", Fabricio has been one of the worlds best grapplers for the last 10 years. JDS isn't a Nogueira Black belt anyway, he trains under Yuri Carlton. There are black belts (Rashad, JDS, GSP) and then there are black belts like Werdum, Maia, Roger and Jacare.
I think Cain will fight Werdum like he fought Nog, he's not really worried about the one shot KO so he can focus on keeping the centre of the octagon and boxing with him.
I thought he was a blackhouse nogueira fighter for his grappling and a luis dorea trained boxer. either way it is very annoying to see this "black belts" as you said like rashad and GSP and JDS when really they are probably hard to submit and that's it when the most important part of bjj is subbing,sweeping and standing up off your back. Hell BJ Penn doesn't do anything off his back but he's an animal on top which is ridiculous that he can do one but not the other.