I definetly think a regular guy could win in a street fight, he'd be more apt to look for weapons and improvise, whereas the mma guy would automatically go to his training.
Doesnt really matter if you got a guy in a choke hold if you get stabbed in the eye by a screw driver.
I can't say where I work, but I work around alot of mma guys and boxers, and sure in their given enviroment they can kick ass, but put them in a room with tables, chairs, bottles, etc. and the playing field is a lot closer to even.