Sometimes your formation is skewed toward certain repeatable battle endings, as I've noticed. If you made insignificant or no changes to your form/equip/runes/etc, it is indeed likely (I don't know statistically how much, but it's definitely not unlikely) that you will end in a similar fashion. This happens for most battles when the opponent's form is constant (ie PVE). Btw, my recommendation is to try and find another form if you only win about 4% of the time.