The Key thing that's mentioned before introducing Crocodile's bounty is the Marines saying the intercepted singles for Crocodile and Mihawk that confirmed their involvement (reference to when Mihawk was talking to Crocodile when Marines had him surrounded).
-> He's one of the two commanders of a Yonko crew, who's captain rivals Shanks (in image)
-> He was able to get Dracule Mihawk to join him
-> Outside of CQC his Devil Fruit is OP (just like most Logia are). Much like how Enel is a scrub in CQC once somebody can hit him, but outside of that has a OP DF. Croco is the same way, if somebody can actually get into CQC with him he gets trashed even by mid-tiers. But issue is how powerful his DF outside of that. Casually putting down tornadoes and etc.
Hence Crocodile's bounty is specifically about his Logia powers, Intelligence & Leadership. The intelligence having to do with being able to recruit Dracule Mihawk (and any potential plans he might've discussed with him off-panel during that call to convince Mihawk). And the leadership due to being 1 of the three faces of Cross Guild. But leadership is the main one out of the three.
Just as Buggy got his bounty from being able to command Mihawk and Crocodile, along with once standing shoulder to shoulder with Shanks:
That's why Oda made sure to clarify everything regarding their formation and clarify why on the poster... which again makes Buggy look like the leader and Crocodile look like somebody who's a peer to Mihawk:
In short: Crocodile leached off of Mihawk, like Buggy did. Mihawk on the other hand got his bounty for just being that strong. We don't know his previous bounty, if it was 3.3 billion and he just got an addition of 200 mil.. not a big deal. You get the point. Where as somebody like crocodile went from at max 240 mil (Oda's projected bounty of him if the Marines knew about his organization and what not) to now 1.9 billion after Cross Guild.
Basically Mihawk turned one into a Yonko, and the other into somebody close to a Yonko (Teach's as emperor was 2.2 bil). There's no "retconning" Oda is doing here with these characters. It's just Mihawk's hype using Buggy & Crocodile's bounty as the tool. (And partially Shanks hype since Buggy's hype is in part due to Shanks as well). Just Oda showing how PERCEPTION is a huge thing, something he's been doing since the start of the manga.