Marco is not close to yonko/admiral tier. His attack (in combination with Vista as well) was treated like a mere annoyance and an admiral accepted to go against him and his whole group of WB pirates combined (Jozu excluded) and Crocodile, while trying to get to Luffy. Him and the other WB pirates were also destroyed by the BB pirates, people that just a year before were instantly running at the sight of an admiral.
Though his performance with Big Mom was definitely noteworthy.
Marineford Power Scaling is absolute BS compared with the New World tho.
Oda had no idea how Haki was actually working in that shit.
Jinbei didn't know how to use it, even tho he fought Ace for 5 days, without Haki?
Akainu took hits com Marco and Vista while saying they were using Haki, but they couldn't damage him. Whitebeard was considered the Strongest Man in the World, but from what we can see of the power scaling on Big Mom and Kaido since then, shit is kinda weird.
okay i'll write a sentence about dragon's part here: Dragon came to wano to meet oden to know about true history of world but since he was dead, dragon decided to find history and act accordingly and his tattoo is symbol of his conviction(and luffy was born in Wano)
@Pantheos this is kinda like teaser of my theory, should I expand on it?