I can see zero technical deterioration. None whatsoever. Aldo remains razor-sharp. I think that, technically and in terms of ring generalship, he is at his absolute peak.
He might be the best P4P in the sport. Absent his reach advantage, Jones would probably be wrecked by Aldo in a hypothetical bout.
You can even make a case that in terms of raw materials, Aldo has the most ever. Great boxing, the best leg kicks in the sport, arguably the best reflexes in the history of the sport (adding up to being one of the best strikers in MMA history), the best TDD and defensive wrestling in the sport's history, and (apparently) top-level BJJ. His one weakness (and it's a real one) is his cardio/conditioning. That helped Edgar to push him to the brink of defeat. But Aldo is superb. He is so good that he rarely has to come out of second gear to outclass brilliant MMA fighters.
And, believe me, this is begrudging. I'm not a fan.