Luffy knew he was weak when his crew got shitted on by kizaru and kuma he knew that he was not the biggest fish after all and decided to get stronger whereas Captain "narcissistic" Midd thought he was top tier and got fucked in this process. If he realised and got trained he would be a little bit close to being rival to luffy. Maybe he has a change of heart after his humiliation by shanks and he trains a little bit.