Just to be clear. When you are standing face to face or face to chest in this situation, and there is typical prefight shit talk going on, there is no such thing as a sucker punch. If you aren't expecting to be hit or thrown at that is your problem.
Way too much attention is being paid to the "professional training" If I go work out at a gym and have 30 days training from a personal trainer, I am not a "professional weightlifter". Just a dude that works out. The mma guy didn't do anything that any 1 or 2 year varsity wrestler with 3 months of BJJ wouldn't have done. You can watch 5 mma fights and figure out how to put someone in a rear naked choke. The fact that mma guy couldn't hold tough guy holder in a rear naked choke tells me all I need to know about both dudes. MMA guy did a nice job of getting in the hooks on the legs (common wrestler move), however, when you are fighting, there is little to no reason to try and "submit" your opponent. A "trained professional" would have kept the legs in and beat the shit out of the guy from the top while the "holder" was on his belly just taking blows to the head.
How is that for watching a tape and making a bunch of suppositions??