I think some of misunderstanding King's durability or defense and his speed.
Even when King flame is not behind his head he still has incredible speed and impressive durability/defense.
Zoro didn't blitz King with his fast ultra tiger attack.
King was hit in the face with part of the attack and it didn't cut his face. Only his mask was damaged.
I'm sure there's information missing since it's a very short summary. The full summary should give us a better understanding of King's inquire power.