Lack of power? Is this the same ''lack of power'' that had JDS being quoted as being completly unable to remember anything from the first round and forward of the second fight, and from the second round and forward of the third one? Werdum would die or tap long before he'd take the kind of punishment JDS did. You really don't understand how significant the amount of damage JDS sustained were in those fights, Cain took months off of JDS fighting career. And Werdum isn't much of a threat on the ground, most of his finishes are after hurting guys and then locking something up.
Look at all of Cain's fights he NEVER puts himself in danger on the ground, he's always on top and never leaves himself open, instead he throw vicious GNP that ends fights. Werdum vs Cain would be Werdum getting murdered by the pressure & pace Cain sets, and as been said Werdums gastank blows c'ck. And Cain wont use his wrestling for takedowns, he'll use them to keep Werdum guessing while Cain dirty boxes him to hell against the cage.