The impact of a few deep links appears be greater than what you might first expect. In today’s post I am going to explore why that may be the case, and how to leverage it. First let me go into my theory on the matter. For this example, let’s assume we have a high PR home page (PR7, 8 or 9). Let’s say it has 3 layers of content, consisting of an upper layer (categories), a 2nd layer (sub-categories) and a 3rd layer (detailed content).

If we apply the traditional PageRank algorithm, even the 2nd layer and 3rd layer pages should be somewhat competitive because they receive of PageRank from the rest of the site, but there are a lot of times when this does not seem to happen. It looks like the domain authority and trust is not distributed across a site in the same manner as pure PageRank. My theory is that this is caused by a filtering mechanism, which restricts the way that the lower layer pages on a site can accumulate the trust and authority of the domain.

Perhaps the page has a potential amount of link juice it can receive from its own domain, but if the page does not get any links on its own, then not all of that link juice is credited to the page. Here is an illustration showing what I mean :

When you get a deep link to a 2nd layer or 3rd layer page, our testing at STC shows that it has a much bigger impact than you might expect. Even a relatively low value link seems to bring large benefits to the ranking and traffic potential of the page, beyond what you would expect the value of the link to be. This may be because in addition to the link juice of the link, it also enables more of the link juice available to the page from the domain to be passed through, as shown here:

And as you add more links the affect becomes more pronounced, as shown here.

Summary

Chances are the the actual algorithms that result in the behavior we have observed over time are actually quite different in concept from what I have outlined here, but this mental model of the value of a deep link does work for our purposes. When you have a 2nd, 3rd, or deeper layer page that you want to push in the rankings for competitive terms, you don’t necessarily need to get it hundreds of links. Just a few links will provide the page with benefits on a much larger scale than you might otherwise think.