The ちょっと used in Kizaru's sentence is quite ambiguous.
The "Little" can mean "A Lot" especially when the character is trying to be polite.
It won't hurt you to admit that Kizaru took a heavy blow from Luffy and that one blow was enough to stun him to the ground, bro.
Hopefully Kizaru will do some damage to Luffy in round 2, it's pretty unfun when an Admiral keeps running away and gets dropped with 1 blow.