Werdum could be a legit challenge for Cain.
Cains strength has always been aggressive tempo with either dirty boxing from the clinch or relentless takedowns. Werdum is extremely dangerous on the ground, and he has markedly improved MT over the past 6 or 7 years. MT guys *generally* prosper more in dirty clinch work than boxers do, which is Cains staple for striking.
I could see the fight honestly going just about any way you could imagine. Early KO from either guy. Cain wearing Werdum out. Werdum getting the better of a stand up battle and eeking out a decision. Cain via GnP, Werdum via sub. Both guys are dangerous, and Werdum has just about the right tools to present an actual challenge for Cain. Werdum HAS been known to shit the bed occasionally, so there is always that risk but if Werdum shows up at his best it could be a barn burner.
JDS is about as one dimensional as you can get, he's a heavy weight Chuck Liddel, and as such his striking can be brought down a notch when he has to fight first to not get taken down. Other than that first fight flash KO, I really do think Werdum presents a very interesting stylistic challenge for Cain as well as his biggest challenge to date and I look forward to this fight about as much as I have for any HW fight since Fedor was fighting.