@CosmicDebris:
Too many semantecs. Is it really important whether Arlong may have had potentially more physical muscle mass without a DF? I don't think we need to wonder whether Arlong could beat up Crocodile if Crocodile didn't have a DF or not.
Well, the whole point of the argument is that even though Arlong sucked at combat, he was physically imposing. That sets the bar for future fishmen. Sure, Crocodile and Lucci could clean his clock 9 ways to Sunday, but the point is, Arlong is probably immune to gunfire like Luffy because of his shark body.
This is part of my theory that Jimbei will be the Brolly of One Piece: A fighter who can't fight for shit, but is physically stronger than every other fighter. It's like Toguro in Yu Yu Hakusho. Toguro wasn't that great a fighter, but he was so damn strong that he made up for it.
Arlong wasn't nearly that strong, but Jimbei very well could be. As far as we've seen, most of the Gyojin are arrogant, angry folks. In combat, they suck. But physically, they are much stronger than most humans. In the 10 years where Arlong was slacking, Jimbei could've been physically training.
You're right, Crocodile and Lucci were superior to Arlong in every way, but not in raw physical strength. Which is why people compare him to Jimbei. Jimbei is probably a better fighter than Arlong, but like Brolly, simply uses strength to overwhelm his opponents.