How is Battle Activity calculated?

From this forum thread, Battle Activity is calculated in the following manner:

It takes into account your battle time and the points you've earned. If you have the most points in your team and you were in the battle all the time you get 100%. So, its A x B where

A is the leader point divided by your point

B is the full battle time divided by your battle time.

Thus, it looks like to get a Battle Activity of over 80 over 5 battles, your goal would be to be as high up on the leaderboard for your team as possible and to stay in the battle for the entire duration.