"Seeing" frenzy

[Kodaly]

You should see the Frenzy animation when your stack kills an enemy stack, and then after that you should see that you now have the +Attack increase mentioned in the description.

I just noticed that the description in the game of Frenzy is that it's simply a bonus to all attacks--not only after killing an enemy stack. I may be reading you wrong on this, but you may seem to imply that it's necessary first to destroy a stack to get the bonus. Which is correct?

EDIT: You are. I just played through a couple of battlefields, and noticed a significant bonus after one stack of mine defeated two of the enemy's. Another of my stacks that hadn't done more than soften up the enemy showed no bonus at all.