I have no doubt that Cain will beat JDS if he can get the fight to the ground regularly. There's no reason to believe JDS has anything for a wrestler of Cain's caliber from his back. In fact I don't think anyone in this HW division has anything to offer when held down by Cain. I doubt JDS will end up on his back much though.
Rookie Hammer Squad 2015
Frankie Edgar - Dominick Cruz - Jorge Masvidal - Cat Zingano - Holly Holm