Buggy already has the lock on biggest pirate crew seeing how he is a pirate "distributer". Aside from his origins with the PK I can't understand how they would put anyone weak up there. They still need another 2 marine admirals to shift the balance back. Now that sakaizinu is fleet admiral, only kizaru is the sole admiral in the fleet. Ao kiji is roaming. Unless they gave rob lucci another title there's not much firepower on the marine side. Fortunately the supernovas are planning to wreck what's left of the balance by messing with big mam and kaidou's empire. With Whitebeard dead that would leave shanks kaidou and big mam also at each others throats for territory and balance in power. In terms of the balance of the sea this leaves every plateau shaky except for the revolutionary side. They have been making some moves behind the scenes during the time skip. When we spotted robin at that prison she was freed by the revolutionaries. They might have picked up some momentum in force by freeing some potentially strong people akin to what impel down did for the WB WG war