Recent Vol. 78 SBS revealed part of Crocodile's backstory
D: I have a question for Odacchi. In "The White City", chapter 762 of volume 76, during the scene where Law stabs Cora-san, I found Crocodile printed on the paper Cora-san was reading.
So what was that article about? P.N. Yamamoto・Sugiyama・Hori
O: Yes. I'm quite impressed you found this one~. As you've pointed out, if you look really closely, you can find Crocodile there.
This was from the time when Law was 10 and Doflamingo was 25; 16 years ago from now. Crocodile was 30 at the time.
Similar to Luffy, back when he was young, Crocodile's name spread across the seas with incredible momentum, but soon after he was admitted into the Shichibukai in his mid-20's, he tried to fight Whitebeard and was completely and utterly crushed by him.
Though he seemingly calmed down at this point, his eyes became set on the kingdom of Alabasta, and it happened to be precisely during this time period that he was being featured in the papers as a hero who hunted down pirates. In other words, that was an article reporting the acts of heroism by Crocodile at the time!
source
nepiecewiki
Seems like our predictions in that regard were correct.
Now about his powerlevel:
First off, let's take a look at the first fight between Crocodile and Luffy, and see what we learned from this fight. Luffy is fast enough to dodge Crocodile's attacks, and Luffy is strong enough to cause Crocodile pain if he manages to circumvent his intangibility. Losing this fight was in no way a shot against Luffy; Whitebeard would lose to Vista if he had no way to hit him, so this is in no way a huge point in Crocodile's favor either. Luffy actually managed to visibly agitate Crocodile twice during the fight due to his sheer persistence and forcing him into sand form, so if anything that's a point in Luffy's favor. Second Fight, Luffy continues to show that he can dodge Crocodile's techniques, and he also showed he was able to land powerful blows against Crocodile. Unfortunately, Luffy was still at a large disadvantage because he was dependent on an unreliable barrel of water to do damage, and water Luffy was also completely unreliable because Luffy had to shoot globs of water at a guy whose ability allows him to absorb water if he wanted to land a hit.
There were only three things different about the third fight with Crocodile.
1. Luffy had a reliable way to hit him
2. Luffy now had strong knowledge on his techniques
3. Crocodile finally decided to treat Luffy as though he was a true pirate
Aside from that Luffy dodged his techniques, connected powerful blows, used his ingenuity to catch him off guard, and finally overcame Crocodile due to his trademark perseverance and determination. Not a single panel of that fight was inconsistent with what we had seen during the previous two fights. Crocodile fans just don't want to admit Luffy's victory was legitimate because god forbid Crocodile looks any weaker than they hype him up to be.
Good analysis here. Anyone who doesn't acknowledges Luffy's clear victory disregards what's actually on paper. Even though it was a clear victory, it was still not an easy win, which is due to Crocodile's good reflexes, good stamina and the poison (which is cheap, but should still be considered).
Now let's talk about Crocodile's supposed retcon. First, the reason people claim he got a retcon was that he was "hanging with the big boys"... though you'll notice most everyone who plays up Crocodile's war performance conveniently fails to ever bring up the fact that Luffy straight up swatted away his assassination attempt at Whitebeard like he was a toddler caught reaching for the cookie jar. If Crocodile really became this tough badass capable of handling himself with the best the war had to offer, than he wouldn't have been thwarted like that by Luffy, the guy considered an ant in the war.
Let's take a look at the skirmishes he had at Marineford. Doflamingo, Mihawk, Akainu, and Jozu. Doflamingo wasn't serious at all throughout the course of that fight, if one thinks he was, than they have the reading comprehension of a tapeworm. There are really only three things we see from this skirmish; Doflamingo comes out unscathed from Crocodile's attack, Doflamingo attacked Crocodile without haki despite knowing he's a logia, and that Doflamingo can block Crocodile's hook with his foot. None of that implies he was at a level above his Alabasta self.
As for Mihawk, many people flaunt Crocodile saying he blocked Mihawk's attack. A clear look at the page makes it apparent that it was Mihawk blocking Crocodile. Look at the motion lines on Crocodile's hook, he flew in, swung his arm, and Mihawk blocked. But just to humor those who think Crocodile actually blocked an attack from Mihawk, I'm going to bring up the fact that Daz Bones accomplished the same exact thing a mere page earlier. In either case, neither is evidence he grew from Alabasta, and that's the last we see of it, so there's no reason to assume any additional skirmish happened between them after that.
People also praise Crocodile for cutting Akainu in half. Now cutting a top tier in half is an insanely impressive feat, if it weren't for one thing, the fact that Akainu was a logia. You know who else managed to break through a logia? Virtually everyone whose attacked one without haki or seastone. Nico Robin even managed to shatter Aokiji into dozens of pieces, and Luffy punched pieces of that mast through all three of them. Failing to damage a logia isn't an impressive feat, and it's certainly not something that he couldn't have done at Alabasta.
Now I'm going to get into the single most overplayed feat in the series, Crocodile surviving Jozu's attack. Because whoever is using this as proof is likely abiding by massive double standards. What do I mean when I say that? To start, how often do you see people claim Daz Bones got a massive retcon into high tier because he blocked Mihawk's attack? You don't see anyone saying that because then they would be written off as a troll, because people don't have their fan goggles on when it comes to discussing Bones. Then we have Luffy's performance throughout the war. Luffy got slammed into the ground by Blackbeard and bounced right back up, he got cut across the torso by Momonga, took a shigan from Dalmation, got kicked around by Kizaru, was pelted with lasers, got stabbed by Aokiji, took a clean punch from Buddha Sengoku, survived a slash from Mihawk as well as reacted to his attacks. Yet you'll hardly hear a single person claiming Luffy got a massive retcon during the war. Crocodile gets his head covered in blood after getting smashed by a Jozu he could hardly comprehend and suddenly there's a bandwagon of fans ready to milk that feat for all it's worth.
I don't think Crocodile has got a retcon either.
Crocodile wasn't stronger, however I do thing he was changed and that actually made him look stronger.
Taken into consideration the official backstory I posted above, we know that, just like Luffy, Crocodile once was a Super Rookie. His bounty didn't exceed the 100,000,000 but that is because he joined the Shishibukai before it could. We know from Oda that he is worth more.
So Crocodile had a lot of potential and high ambitions. Then he got crushed and decided to chill in Paradise. The same happened with Moria and both were the first Shishibukai Luffy defeated. They never had any real challenge in Paradise, so their growth stopped.
After Luffy freed him from prison his attitude changed. Trying to get a new chance to defeat one of the big shots, he threw himself against them whenever he had the chance. Because he has a big ego, he always looked super confident when doing this and that actually made him look stronger than he actually is.
If anything the war proved again that Crocodile has great reflexes and reaction speed, as he was always just in time. We already knew that before though, it was said during the Alabasta arc and proven again in an SBS in a question regarding how Luffy could fly into Smoker even though he's a Logia.
Also we don't know for sure if he really doesn't have Haki since he was introduced before Haki was, there was no visible indicator for Haki preskip and he always attacked with his Devil fruit and hook which work against Luffy anyway. It doesn't really matter as it wouldn't have changed his powerlevel. Even if we assume he did use (invisible) Haki on all his attacks, the results would still be the same and it would actually only imply that his Haki was weak. He will definitely have it now though.
I think powerwise preskip Crocodile is around Super Rookie strenght, whatever that means. He does have a lot of potential though and will come back a lot stronger.
I also have a cracky theory. Crocodile's ability to draw out water to turn things into sand is strikingly similar to Doflamingo's ability to turn things into strings and draw them out. Crocodile is the only Logia user shown with such a secondary power aside from the special Blackbeard.
Crocodile always boasted about his fruit mastery and he does know about awakening, so him having it doesn't sound too farfetched. This still doesn't make him any stonger than he really is, but it could be the reason why he was invited into the Shishibukai so early in his carreer.