It seems that SPF must play a pretty major role. I have been testing some things with another player who is level 4 and I am level 8; I have more powerful items and yet when I am not active in the hour leading up to battle I lose everytime - but if I am active then I win.
so the only difference seems to be the SPF (and the fact it can overpower my level/item advantage)
I heard from @jedigeiss that they are still balancing the SPF... maybe it won't matter that much in the near future (: