The real problem with Aatrox--the only top laner with no defensive ability
His passive is basically die, come back with low health and no attack speed, and then die again.
But as far as usual passives that keep him alive in a fight, he only has attack speed bonus when his bloodwell is full, which will help him lifesteal more often. Easily shut down with items and abilities.
Lets look at all the other top laners
Jax--Can parry damage, gets bonus armor and magic resist with his ult that scales off of AD and AP Olaf--Passively gains resistances Jarvan--can shield himself for 5 seconds Fiora--can parry incoming damage and CC Tryndamere--can become invincible Nasus--Gains health and resistances when he ults Riven--gets a shield that scales off of AD
Need I go on? They all have defensive abilities that allow them to stay in the fight. Aatrox is the only one that doesn't have this.

