Cain has the size, but I wouldn't say he is a better grappler then Weidman or a better striker then Bones. But he does have the size and power advantage and his chin would hold up to whatever either man had to offer. I think Cain beats both. I just don't agree that he is better then both in all areas.
I'm not so sure about that. Bones doesn't have one hit KO power but the dude has some vicious GnP that I think could make any man want to stop fighting.
Weidman just KO'd a dude with a very solid chin. As well as his elbow against Munoz who is a very tough fighter.
I don't know if either fighter could get the position to execute against Cain, but I think both fighters at a very simple level have the power to do it.