How do you know they are weaker than flying 6
Portrayalwise, they seems beeing the youngest and newest members of the flyers, in portrayal Sasaki,Drake and of course Who´s Who get placed above, Black Maria more in mid range:
Who´sWho=>xDrake=Sasaki=>BlackMarie=>Ulti=>Pageone
It is my own though but I would place Ulti and Pageone as the weakest flyers, beeing strong but not like Who´s Who, the one who come close to a calamity.
Read this comment in another side and thing too:
Sir Curlyhat:
If this guys are so durable imagine how much of a tank someone like Queen is
Jack,Queen and King going be insane monsters, I can understand why Oda save them for the last stage together with Kaido.
Im still thinking that they get defeated in teambattles.