User blog comment:Traffy731/Kaido is going down/@comment-3177613-20130126145654/@comment-3425840-20130126194317

Yes, Luffy is stronger than Rayleigh and that is the reason he almost died against Hody! And it took him several attempts to finish off Caesar! Hell when he went off to fight against Jinbe, he was only keeping up, not dominating.

Against Hody he commented that his haki was not strong enough yet to take on a bite like attack and he got wounded.

If memory serves, Oda said in some SBS that if it was Shanks or Rayleigh, they could possibly KO the whole 100000 goons at FI by haoshoku haki, not just half like Luffy.

Just because Rayleigh left after 1.5 years saying his training is over does not mean Luffy was as strong as him at that point. If training under someone necessarily meant surpassing him then it implies that Zoro is already the strongest swordsman in the world and thus his dream is fulfilled.

As for Luffy beating Kaido, the only ways it can happen are either with the help of some one at Luffy's side during the battle or by huge plot armor (like with Crocodile) or some absurd condition (like with Enel) or if Kaido was weakened to begin with.

We don't need to know Kaido up close, just his position as a Yonko is testament enough of his might.