Marco isn't someone you can just beat fast regardless of rank, yet he still went down at the same time as Jozu with kairouseki, because both of them were distracted, so not much of a difference.
Regardless, as you say, Marineford has bad scaling, which is why I didn't bring up Marco, but Rayleigh and Whitebeard.
Beating King and Queen is impressive (Weevil isn't, that thing can't be taken seriously yet), but pissing himself over Shanks' haki is bad portrayal. I get that Shanks having his crew there was part of why he would choose not to fight, but it's not part of why he was shaking and sweating.
So he's still the admiral with the worst portrayal.