If you train bagua and get into a fight and beat the other guy, then your bagua trained paid off.
That is the most simplest way to see these things.
HOWEVER, the issue is NOT that, the issue is one of HOW did you beat the other guy and it is this "how" that confirms that you beat him with "bagua" (whatever hat may mean).
In short:
If that Bagua YOU were taught and that YOU train is strictly palm work and circular movements and you beat him with a straight punch up the middle, then while you training MAY have helped you, it certainly wasn't a "bagua technique" that did it.
It would be like saying that you spend all your time in BJJ class working on ground work and then in a fight you take out a guy with a left hook and claim that BJJ is the best !
That makes no sense whatsoever.
Psalms 144:1
Praise be my Lord my Rock,
He trains my hands for war, my fingers for battle !