It's not entirely mysterious: because of the way votes are weighted, the timing of the first two or three really matters. If you manage to get them while you're still on the new page, you have a good chance of getting on the front page which is the only way to get much exposure. If you fall off the new page without that, your article is essentially forgotten.

This means the success of your article falls down to the whims of the few people browsing `new' at any given moment. If you're lucky, there are people interested in your topic there; if not, your article might easily fall through the cracks. Moreover, since `new' has a very bad signal to noise ratio, most people do not spend very much time there. I certainly don't! So this means it's even more likely for an article to fall through the cracks there.

For better or worse, this means HN misses out on good articles as they fall through `new' without getting votes. To get anywhere your article needs to be both good and lucky.