haha well that's the AI director for you, its changing because of how YOU play
the "stress indicator" watches these things:
your distance AHEAD of players
your distance BEHIND the players
your ammo count
your kill count
your accuracy
your friendly fire count
your health
whether or not you have a health kit
whether or not you have pills
and after it analyzes all that, it desides how best to be a challenging game
the good thing is if you are low on ammo and health, itll give you an OPPORTUNITY to get health/ammo, but most likely will also send your way a hunter or tank