I am not a big pr buff but site in question ranks high because of this simple equation:
PR(a)=PR(b)/links(b) + PR(c)/links…..PR(n)/links(n)
Page rank for a site is calculated using this formula. All linking pages divided by the number of links on each page. However just because you link to another site with a good pr and the site happens to have tons of links this is not valuable. The linking partners on my site I keep at 20 of so. I am pr4
For example; when exchanging links check out your linking patrners links. The less links the better it is for you to link. What I am trying to say probably goes against everything you know about pr. But its better to trade links with a person with few links on their link page. I have seen some sites with hundreds of links this I consider a bad practice. My site is only 5 months old and using some old school knowledge I figured this was the way to go.
But PR does bring people knocking but does nothing for serps. My quess would be the page ranks high because the site its’ linking to has very few recipricol links or the site has alot off inbound links. This would satisfy the equation above.
Consider this, Bank sites usually have a high pr and they are not swapping links. Instead the have alot of quality inbound links. If you got just one high quality inbound link from a pr 5-10 site you could basically take down all your link exchanges. pr1-pr4 according to google are unimportant sites. Just a theory, I hope its not to confusing. Greek39