I think the only problems in PA are the mobs in the middle with very high in physical def and low in magic def, that's why critical damage can kill them because it bypasses no matter how high the pdef is, and magic damage can kill them easily too. In my suggestion lower the physical def equal to magic def and increase the HP 3-5 times the mobs in the middle and increase also the HP of the boss 2-3 times. And you mentioned safezone but actually there is no safezone inside the PA because you can be killed whatever your location is. Maybe we can suggest in next season that the starting base and respawn area will become safezone but put some condition that once the battle begin you can't stay there in more than 30 secs or else you will be kicked in PA. Another problem is PA time and I agree in your suggestion that make it 4 batches of PA per 24 hrs. Maybe these suggestions will resolve all the problems in terms of different time zone of PPL and damage of every class inside the PA.