I highly doubt they could make an immediate impact without proir training in either submission grappling (like Bjj or Sambo), Wrestling (real), or some sort of striking element (Boxing or Kickboxing). They may be big and athletic, but just that alone won't get you far in MMA. I remember about four or five years ago an NFL footbal player ( I think from the Eagles),challenged UFC veteran and Cesar Gracie protege, Gil Castillo. Basically all that happened was Castillo subitted the guy four times in four minutes (it wasn't a sanctioned bout, just a dojo challenge) I would expect the same to happen to Batista and Lashley, just look a Sean O'haire, and that's because he's been training for a couple years now. I remember reading a Saul Soliz interview (the guy that trains Tito, Ricco, Lister and the rest of team punishment) and he said in order to even hold your own in MMA you would need at least 2 years of Bjj and 2 years of boxing or kick boxing, and that's just for a beginner not an upper caliber fighter.