I don't know. To be honest I think there is no sense in the way it is calculated. It should be updated or something... Currently abandoning rewards the player more than to the adversary... How is that possible?
I think its because abbandoning is seen as a way to speed up matches so its allowed (Its annoying when your trying to do missions but Its fine when your just trying to win) but timing out could be used as a way to waste peoples time so its punished more.