@Chrissie:
Waitta minute~! People actually think that sunglasses guy is Crocodile? XD No. Just no. For one he has a rather different body type from Crocodile and his face looks different too. He does look like one of the main crew members on Roger's ship but he is certainly not Crocodile! 
Not to mention that judging by his statement he's a long time member of the Roger Pirates, which considering that Rayleigh said Crocus' three years was only a short period means he's been around for quite a while. And I seriously doubt that Ivankos statement about knowing Crocodile when he was a rookie would go that far back.
Another thing would be the character change. Again the statement of the sunglasses guy in this very chapter is what I would base that idea on. It just strikes as a mix of comprehension, tolerance and sympathy for Rogers pirate-life philosphy. And I just don't think that somebody like that could develop into someone like Crocodile no matter how crashing the defeat to Whitebeard must have been.
In fact, if (as it most certainly looks like) this guy has been together with Roger for many years then he should very well be aware of Whitebeards strenght. Crocodile however strikes me as somebody who's dreams have been crushed and he himself being brought back to reality because of that. That just doesn't mix well with somebody who's been together with Roger for so long.
Not to mention that Crocodile aimed to become Pirate King which I just don't see to be the desire of one of Roger's closer crewmates. Rayleigh doesn't care for it, Crocus doesn't care for it. Heck, of the apprentices even Shanks doesn't seem to give much about it since he put a bet on the new generation. It would seriously surprise me if "Sunglasses" out of a sudden would have developed an interest in that albeit all which I've listed in this very post is hinting towards him being not that kind of guy.
But if all of that is to philosophic then perhaps I should make use of some more simple minded reasons. Does that guy wear any coat or smoke cigars? No. But Ivotas, he might have developed that thing later on. Yes, he could have but that's rather unlikely. With this chapter we've just found out that Crocodile smokes cigars and wears pimp(madam) coats for at least 22 years. And I just don't see a radical style change for someone who's been around for as long as the sunglasses guy.
Another more simpler reason: Do you guys really think that the WG would invite a former Roger Pirate into the Shichibukai? I mean for real? Keep in mind that this guy is a long time crewmate of Roger. You really think the WG would pull another Buggy with him?
@GaaraofTheDesert:
Anyway this guy.
http://images2.wikia.nocookie.net/onepiece/images/f/f9/Roger_unknow_pirate.jpg
could be Kaidou. I mean Shanks is supposed to be fighting him right now and this could be really intresting. The two newbies who carried Roger's will and each one of them chose his own way…...this would be a nice rivalry.
His statement from the very page that image is from proves that he's not a newbie on Roger's ship.
