I don't think anyone is a "fraud", Oda doesn't create frauds.
- Dragon and Mihawk are saved for the last. Just as how Shanks didn't do anything combat vise until the last chapter.
- Garp will get his shine when we get God Valley flashback, or when he does his last stand against BB while out of his prime.
- Kid isn't a fraud either, unless you overrated him way too much to begin with. He's pretty strong and above most commanders, but got hit by character having one of the highest attack power (swordsmen have high AP for their tier). Still it shouldn't have been a one shot tho IMO
- why is Coby a fraud? Nobody hypes him up as exceptionally strong.
But the closest would be Law and Kid bounty. Not because they are weak or something, but because they simply aren't worth that. To put in perspective, Yonko BB only had 2.2 billion after everything he did. Along with having a solid crew and most territories of WB, he also was stronger than either of them.