[zenith]

I knew I wasn't clear enough.

Simple answer. Assume the following:

You are at a 50 power level.
Your opponent is at a 45 power level.

Now if you attack and win you gain 1 and he loses 1.
If you attack and lose, they gain 4 and you lose 4.
If they attack and win they gain 4 and you lose 4.
If they attack and lose, they lose 1 and you gain 1.