Well, Matt kind of owed us a deeper explanation and he’s obliged over at his personal blog.
It’s a lengthy post, but here’s what you need to know:
- This devaluing of PageRank sculpting actually happened “more than a year ago” and you didn’t even notice! That means that this change is not the big bombshell we all thought, It’s kind of like getting annoyed that your cable company took away the National Geographic channel a year ago, but you’ve only just found it.
- We get official confirmation that when you link to another page, PageRank flow sees a “decay factor” of “10-15%.” Again, something we’ve known, but Matt confirms.
- Also confirmed, linking to a good site helps your rankings and conversely, linking to a bad site can hurt them. Matt says, “In the same way that Google trusts sites less when they link to spammy sites or bad neighborhoods, parts of our system encourage links to good sites.”
- It’s unlikely that Google will reverse this change: “…we do not expect this to change again.”
The comments make for interesting reading too! Danny Sullivan expresses concern over how the change will affect blogs that get a lot of comments:
Say I have an article on a blog with 5 links in the editorial copy — some of those links leading back to other content within the blog that I hope to do well. Then I get 35 comments on the article, with each comment having a link back to the commenters’ sites. That’s 40 links in all. Let’s say this particular page has $20 in PageRank to spend. Each link gets 50 cents.
A valid point. After all, if you write a post that becomes wildly popular–and gets a lot of backlinks–you’d prefer to flow the PageRank back to your own pages, right? Well, if it’s so popular that you get 200 comments, Google’s going to evaporate a lot of that PageRank flow.
Still, using Nofollow is valid for those links that you simply don’t trust, or don’t want to help achieve rankings thanks to your links. As Matt clarifies, “Nofollow links definitely don’t pass PageRank.”
And lastly, deep in the comments, Matt provides one sentence that basically sums up this brouhaha:
Yes, I would agree that Google itself solely decides how much PageRank will flow to each and every link on a particular page.
And that’s all you need to know.
PS. For those looking for ideas on using alternatives to Nofollow–so you don’t lose PageRank flow–take a look at SEOmoz’s excellent advice.