Funny how different people have different understandings of "success" :) This seems to mention the score and how likely something is to be on the frontpage, none of those things would mean "success" to me. The value from Show HN isn't from the eyeballs, your website analytics reaching higher than before or the score of the HN submission, the value sits in the conversations and discussions you'll end up having in the…
Well, the amount of valuable comments that would form a good discussion is highly correlated with the time a project being on front page, isn’t it.
But I think that requires eager participating from the submitter as well, not just drop your project and not replying to anyone, or not replying with an open mind/required perspective.