While I agree that Weidman would probably beat Bisping, I think you're seriously underrating Bisping if you think that he would lose to the likes of Lombrd, Belcher, and Boetsch. I've only seen Rockhold fight once or twice so I can't make an accurate estimate on the outcome of the fight, but if Jacare Souza can give him trouble I doubt Rockhold would fare too well against Bisping. Lombard and Boetsch would be kept at a distance and jabbed to death. Belcher would be clinched and outworked by Bisping.
Jacare would eat Bisping alive.