There's a difference between the likelihoods displayed and what players think they mean of course. Particularly with sneak attacks and first strikes and anything else that could change the real start of battle odds calculation. The game doesn't break down what happens when one unlikely hit takes place in the first round that changes everything about the chances. The battlefield promos do take from the beginning of battle odds and those odds recalculate every single round during the fight.
My comment on the random generator goes back to experiences with the original game as well though... it's always been that there are an unusual amount of unlikely upsets.