Doesn't this nearly confirm that the Gorosei are indeed capable warriors?
Literally nothing about the World Government's power structure makes sense if the Gorosei are not powerful.
They thought the most hyped old men, in a series full of badass old dudes, needed to be babysat by Admirals. Ugh.
Works well, too.
Marines = stronger than every individual Yonkou crew, but unable to fight two Yonkou crews at once
-3 Admirals
Yonkou = Could beat the Marines in alliances, but too divided and untrustworthy/untrusting to make alliances work
-4 Yonkou
World Government = Possesses an Ancient Weapon (most likely), and is ruled by "The King of the World" Imu. Unknown force, but by ruling the world, the strongest force
-5 Gorosei
As long as the Marines and WG are allied, the pirates are fucked. Which is why Sword exists, to weaken the WG for the final battles.