Aatrox, imo, would be fine if his base stats weren't absolutely fucking abysmal. He got no real adjustment to them while also losing his near constant AS steroid in the early game, effectively losing all early game pressure. His kit and new Bloodwell require him to be able to stand and fight in extended trades but his early durability is so fucking terrible that he can't fight anyone, making the rest of his kit fall apart.
Black Cleaver is great on him because the CDR at least allows more usage of his Q and E to patch up some of his mobility/chase issues and allows him a bit more access to disengage and poke during the stage of the game that he's weakest. It would be good on him even if his base stats weren't terrible, but it's the only way that you can salvage his shit show of an early game right now.