So the investor's knowledge about your project determines the founder or teams quality?
Sorry, I guess I was a little too cryptic. No, the investor's state of knowledge doesn't determine the team's quality; it determines the investor's estimate of the team's quality, and thus the likelihood that the investor will invest.
Why is it more likely that you're not good to begin with?
Simple: most startups fail. The vast majority, in fact.
It doesn't have to duplicate the YC formula in order to be successful
Perhaps not, but note that YC has been considerably more successful than most angel groups. There must be something out of the ordinary they're doing.