In this forum most of the people troll, you can't have a serious thread, especially about powerscaling.
Oda has created most of the admirals different than the yonko and some others like Garp. Of course the admirals, Akainu included, are not as strong as the yonko at their prime, but they pose as an other kind of threat, having mass aoe df powers etc. Powers that wouldn't fit for an antagonist of an arc, but fitting for someone that poses a threat.