I will say that we can't automatically suggest a character is using weaker attacks as that may become a topic of discussion for each and every shounen character (granted, Whitebeard was wounded before he ever started fighting, but besides the point)
A character may display a 6-B feat, then proceed to fight a character, only displaying feats that'd be calculated at tier 7 or even 8, yet we'd still consider them to have 6-B AP and their opponent is 6-B in durability (unless a special case is displayed--which there KIND OF is for the Admirals due to intangibility).
I do not believe the Admirals should be 6-B (in fact, I'm 100% against this), but I do believe they should be higher than High 7-A considering how both Kizaru and Akainu each got the better of Whitebeard at some points of their fight.
Might I suggest the following (Regarding AP):
(This is nothing new and generally accepted) ALL Commanders are believed to be scaled from eachother. I bought into this idea as well, but now view that as pretty hypocritical and we have no real reason to scale them to eachother. Instead, they should scale from their showings against each of the Admirals.
All Admirals should obviously have Dura Negation on their profile due to the nature of their attacks. Aokiji via freezing, Akainu via heat, Kizaru via heat
Aokiji should be the anchor for this chain. He should get his High 7-A scaling from being at least comparable if not stronger than Doflamingo due to the context of their confrontation on Punk Hazard (for the record, we can't use bias. There's no confirmation Aokiji is > Doflamingo despite the vast majority including myself to believe this to be factual).
IDK where the whole Doflamingo downgrade discussion is at, but it should be clear that I disagree with it
Akainu scales from Aokiji for defeating him.
Marco scales comparable (Likely) to both of them for fending off Akainu multiple times, and kicking Aokiji away from Luffy.
Kizaru scales from Marco for taking hits from him, and contending with him in a fight.
Jozu scales from hurting Aokiji and battling him for a brief period off-panel.
Vista scales from being a threat to Akainu.
Here, we have a very clear and concise scaling chain using Aokiji as a base (technically Doflamingo/G4 Luffy, but ignore that)