All the problems with top tier portrayals is coming from Oda OVERPROTECTING the big players. Oda simply refuses to have top tiers fight each other UNDER ANY CIRCUMSTANCES. Which causes the result that we have: a top tier appears, everyone is hyped, then the top tier disappears without fighting anyone or doing anything. Greenbull and Blackbeard are perfect examples for this!
There's nothing wrong in top tiers fighting, losing and coming back–nothing wrong at all. That doesn't dehype them, especially when the author can put top tier X in a situation where he cannot win so by losing he doesn't dehype himself. For example: Greenbull in Wano was against one top tier + multiple high tiers and commanders, there's no way that he can win with that–so he shouldn't. And a good author can make Greenbull look good why losing showing that he's fearless and doesn't back down. Instead, we've got the humiliation with Shanks.
Then we have the Blackbeard situation, where Oda had to hype the SSG, but he simply didn't have any character for that purpose, so he used Blackbeard. And in order to save Boa from certain death, he pulled the Rayleigh card, and then tried to fix things by having Rayleigh to admit that he's weaker than Blackbeard.