Actually, after observing the people I get matched against and who wrecks me and who doesn't, I happen to know that I play at approximately a Silver IV level when I'm on a champion I know how to CS with (when I'm not it's kind of a crapshoot)
I completely disagree with tacos about a rank's meaning.
But anyway, Fizz is a difficult champion to pick up in comparison to others, so there's always the chance that he was playing the champion for the first or second time or so.