I don't think we were very good. I don't think we were very good for quite a while.

--- I understand that in the first part he says that they were rather not good. And in the second he either says that they were very good for a short time or that for a long time they were poor? I'm not sure ...
I don't understand your post completely, but 'for quite a while' = for a considerable length of time.
It's about a band, so maybe the speaker intended to say: I don't think we were a very good band (in other words, they were quite poor). I think for a very long time we were rather lousy.

That's how I see it. Am I pretty much correct?
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Have they ever been a good band?
Yes. But he's talking about their past.
They weren't performing so good at first. That's how I see it.
But to call them lousy... I dunno. He's saying very good. So you need to lower a little.
You know like Excelent -> very good -> good -> fair -> poor.
So based on that logic I'd pick something between good and fair.Emotion: wink
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OK. Thanks.