What treatement? Garp went out looking great, and Ray stalled Kizaru and made BB run away.
Weaker than Yonkou, Rayleigh himself said in his prime he could have a chance. Not now.
Garp went out after 1 Stab, 1 Punch.
Someone for a top tier shouldn't have trouble with Yonkou commander especially lower ranks.
Aokiji was only major contender. And he somehow looked worse than old Garp idk how.
But Aokiji still had the fight in him.
So Yonkou>admiral>~Old legends is a given.
Both Luffy and Loki are considered Yonkou by certain fandom btw.