My issue is that it makes zero sense for Coby to have unlocked haki pre-skip, something only achieved by Luffy and maybe Zoro, train for 2 years under Monkey D Garp, the strongest marine ever, and still be a fodder like everyone claims.
realistically, unlocking haki pre-skip and training it for over 2 years by Garp should have given Coby better CoO than Sanji(tbh they are about the same in terms of haki feats).
not to say that he is on par with the m3, just that he is definitely worth more than a captain and shouldn't be judged by rank alone. imo, the only reason he isn't vice admiral is because he is an 18 year old and doesn't have the experience to be VA.