Recently Google updated the PageRank ratings for websites and a lot of sites saw their PageRank plummet. Many webmasters have speculated that Google “slapped” sites who were selling links for the purposes of passing PageRank… but does that theory stand up?
Let’s look at it from Google’s point of view…
If I were Google and I didn’t want sites selling links that passed PageRank, I would do three things…
1: Encourage any sites selling links to use the “nofollow” attribute as part of the link. Making this suggestion places the emphasis on the *site owner* to comply with Google, which naturally saves Google a lot of time and effort. Perhaps “model” sites like this would get a small ranking boost…
2: Modify my algorithm to identify and downgrade any links that appear to be links purchased for PageRank. Sites who display “Sponsored links”, “Advertiser content”, “Ads” etc can be used to identify patterns in ad location and content. Any patterns identified can be fed into the algorithm and used to locate sites who are selling ads but *not* disclosing the fact to their visitors. If those links don’t contain the “nofollow” tag, then the site is selling links that pass PageRank.
I would then ignore those links for PageRank calculations… especially if they are to sites whose content isn’t related to the content of the page where the link is found.
At his blog, Matt Cutts said Google could detect paid links…
“Google has a variety of algorithmic methods of detecting such links, and they work pretty well.”
… then he gave an example …
“when dailycal.org is selling links to casinos or other link buyers, we prefer not to trust those links.”
… and finally Matt refers to “an email from a “text link broker” that included this suggestion:
Most people use words like, SPONSORS, PARTNERS, FEATURED, ADVERTISERS, ADS and other synonymous terms related to advertisers. Our suggestion is to use ‘different’ titles for these ads. Something like RELATED SITES, COOL SITES, RESOURCES, ALTERNATIVE LINKS and so on.
The email later suggests “to use unique locations for ad links like within content.”
To which Matt says… “I wouldn’t be surprised if search engines begin to take stronger action against link buying in the near future.” Matt Cutts Blog, September 2005.
Not surprisingly, that comment now seems quite prophetic. 
3: Downgrade the whole PageRank system. If selling anything up to a PageRank 3 or 4 link was not worth the effort, downgrading all sites by a few PageRank notches would make the business of selling Pagerank disappear almost overnight. All Google would have to to is increase the stratification of the PageRank system… so that more sites are in the lower ranks, and the selling of PageRank would decline substantially. Of course, downgrading Pagerank across the board would just mean that a PR5 page may be equivalent to an “old” PR7 page… but who’s going to want to pay the same amount of money for a “new” PR5 link compared to an “old” PR7 link? And if they buyers disappear, the business of selling PageRank links dies too.
A litmus test for this theory is whether or not your Google traffic falls with your PageRank. My tests show that it doesn’t… which would lead me to believe that the whole system was downgraded. If the loss of PageRank doesn’t affect the amount of traffic coming from Google, then the PageRank change was cosmetic.
I believe Google has done all three… they’ve told sites selling links to use “nofollow”, they’ve most likely identified advertising blocks (especially to “non-relevant” sites) and downgraded those links. They may well have downgraded the whole PageRank system to make selling PageRank links less attractive. I also believe they hit “article directory” sites and downgraded their outbound links too.
One blog comment post I found said, “Actually, if you look at it, it doesn’t seem like any sites are above 5. Maybe 5 is the new maximum.”
I think that guy spoke the truth more closely than he realized. 
