[quote=SoleAccord]
Mei has 2 KG and is barely A rank. KG doesn't mean you're amazing, it means its a trait you obtained through family or in rare cases OTHER means.
[/quote]

Yeah, because Mei had to be balanced after being given the 2 KG. If it was someone skilled in combat in general, like Zabuza, since he's also from the mist, he would've easily been a S rank. Not to mention that one of the two is also a healer(Yin Release)