No it just means that the top 8 people were really freaking good.
What matters is if the character viability changes dramatically which we have no proof
All that matters is the top end of the metagame, which is people placing in the top 8.
If the same people are in before and after the ban, MK clearly was not affecting the metagame seriously enough to warrant a ban, at least at that given point in time.
@ Above: If there's no way to prove character dynamics, which there isn't at this point in time, who's placing is all that matters at the moment. If I were to beat, say, M2k, with my meta, then I'd be all for a ban of the character, but there's no evidence to prove that people who are worse are beating people who are better at the high ends of play right now.
EDIT: To respond to Shadowlink: Clearly people are winning with other characters right now, which means the only possible ban criteria is, once again, people who suck beating people who win.
In a few months, if and/or when MK is dominating the metagame, it will be viable to say he is stagnating the metagame, but at least in this region I can safely say that he isn't.
EDIT2: When I thought about it, overcentralization tends to be caused by skill differentiation. If a character is easy to use, he's that much easier to win with and takes less practice. Thus, anybody smart isn't going to fight the uphill battle of needing to know more for an even matchup, and thus would pick the easiest character.
You're saying this is true of MK: He takes less skill in even matchups than the characters he is even with, character-dynamics wise.