I've just used Open Site Explorer to compare some sites whose (unpaid) Google ranking I aspire to.
They all have higher authority than my site, but the top ranking site out of the 3 I've looked at has the lowest Page Authority, hardly and links (when the others have hundreds), lowest page rank and lowest page trust.
In fact, when you look at the top ranking page (ranks #1), it does not even have the search term in it as a complete phrase.
One thing I do notice is that it does have 100,000s of linking root domains from one linking root domain.
So how can it rank number one on Google?