I think Yonko haters (mostly Zoro fanboys who think mihawk is gold medalist lmao) are playing word games here and some people are falling to it.
These people don't say Yonko are second only to Roger and Whitebeard. They say they are losers like Crocodile, they are basically trying to lowball Yonko as usual, its a classic trolling.
Crocodile was definitely not talking about the people who are still competing for One Piece. Buggy for example said Whitebeard was the closest man to One Piece and Ace said he wants to make Whitebeard the pirate King. The public perception was, as well as Crocodile's, Whitebeard was still searching One Piece just like other Yonko. When Crocodile said silver medalist he definitely meant the people who already lost and end up in Impel Down as a result, or people like who has no chance to find One Piece anymore; such as Moria, Mihawk etc.
How can Whitebeard be superior to other Yonko when they specifically said Whitebeard pirates don't attack Yonko Kaido because they afraid of big casualties? Lol. And Oden was their nakama and they still couldn't save Wano from Yonko Kaido, but then they say Whitebeard rules the all seas. Even Oden said if he can't beat Yonko Kaido no one will includes Whitebeard. Or how can Whitebeard be superior to Yonko Shanks when he attacked him on panel and failed to beat him? Garp specifically said Yonko
are same level with Whitebeard.
If Whitebeard is gold medalist so is the Yonko. If Whitebeard is not gold medalist then Yonko are not as well. You can't separate Whitebeard from Yonko based on an out of context statement from Crocodile and same Crocodile said later Whitebeard is pathetic and weak man. Crocodile changed that from gold medalist to pathetic weak man.
As for Roger, he never beat Yonko Whitebeard. He begged Yonko Whitebeard and Oden to be the pirate king. His superiority to the Yonko might be his begging skills.