Except luffy was stronger than croc, luffy was always physically stronger or equal to everyone he fought, it was just that he needed to figure out the trick to beat them. Against kaid, he was completely overwhelmed in physical stats. Thats the difference. Kaido blitzed him, he one shot him, and took no damage from him. You wanna tell me in a couple of days he goes from that to doing the most damage to him? Sure he can hurt him now. But there are levels of damage he can do, i doubt hes gonna go from doing no damage to doing hard/serious damage. It would be bullshit of thee highest order.