1. Mihawk is irrelevant to the story. You can remove him from the story and nothing will happen, that's how irrelevant he is.
2. If power levels exist in one piece, I don't believe in them anymore, then Rayleigh is much weaker than people give him credit to. He's definitely weaker than Oden.
3. Power levels disappeared from one piece since timskip.
4. Luffy is mentally ill.
5. If power levels exist, then Akainu is the strongest Admiral that ever existed.