The issue is that he feels really bad to play due to having basically no AS when he doesn't have blood rush, and because he can't keep it up by staying in combat with minions/neutral jungle monsters, you can just walk away from him when he has it up.
That and he can still be CC'd out of his Q, which as a diver, is his tool that he uses to dive. And Blood Thirst is useless in its new iteration; unless you're playing tank-aatrox (which is bad because you do no damage) you're better off building Death's Dance and sitting on Blood Price, which will give you more healing. And Riot significantly nerfed Blood Price early.