I guess since they say that you have to be in the battle for minimum 5 minutes to be event-eligible, then if you win when you exit the battle after 5minutes with a win, that should count. At least thats what common sense would suggest, though not 100% sure if this holds true in this game nowadays :-).

I just saw there was a post in game updates that said it is indeed 5 minutes only. The reason I asked was because the last event that counted wins you had to stay the entire battle.

problem with most wins event is if a couple ppl are on vent/Ts or other chat programs they can ask there buddy what other team attack is and determine if they can leave game or not. I am guessing this is also how some ppl have great win %.. or disco's.
Also this event isnt geared to those that have a real life.. the ones that spend the most money on the game.