updated 19 November 2010 : Bob Sakayama
The primary differentiating factor between high level search and basic optimization is the focus. Webmasters and most developers chase keywords because it's cheap, easy and works. But the enterprise requires much more than a good guess of the targets. It requires a robust foundation built upon in-depth knowledge of all the keywords and an architecture that can handle very large numbers of targets. Structural seo is a very powerful optimization strategy that is driven by the keyword semantics and enabled to scale no matter how large the keyword universe.
Seos working in well defined niches can probably succeed with relevant content, fundamental seo, and a lot of work. And those who have found success by only buying links will believe they also have the keys to rank success. The fact is, that while these easy methods work (forget whether they're compliant), they work up to a point, but their limitations begin to become more and more obvious when the strategy has to address a competitive market or when it has to scale large. There's a big difference in getting 50 products to rank compared to 500,000.
In the web world, people tend to copy success, so the strategies used by sites at the top of the search tend to get replicated everywhere. The real problem is that doing what everyone else is doing is the path to mediocrity because it doesn't contribute to the solution set, it only mimics common knowledge.
The answer clearly lies in not following the crowd, but doing it better - perhaps using the common knowledge to push out into the wilderness a bit. And while there are always uncertainties it's not the unknown frontier you might expect, because enough time has elapsed since Google became dominant for some very revealing, scientific experiments to have been conducted on live enterprise level environments and experimental sites. For example, our experiment to test the original nofollow rules also detected the change Google made to those rules within the first 7 months of introducing it.
The 2 common factors in the new strategies coming from these experiments are (1) the critical importance of semantic detail, and (2) the significance of PR flow. We now know that PR is passed along with semantic data, and it is in addressing this combination that the enterprise can perform in the search. Structural seo creates a targeting architecture that optimizes the PR flow - cascading out from categories to long tail, while also addressing the semantics with strict nomenclature rules (the naming conventions applied to files, urls, tags, etc.) for code, links, filenames and content.
Like the pig whose house is built of bricks, a robust semantic structure will stand up to competition by enabling optimization to occur on difficult targets over time, through focused content builds. Because it is primarily content based, its results are persistent - should last as long as the site does. It works by always addressing both individual targets, as well as the overall semantic structure, enabling the site to 'convey' relevance through organization.
We developed an organizational structure called a 'power center' to group closely related targets into structures that semantically support the category level term (the one that's most difficult to rank). This technique requires research in advance of implementation and strict attention to nomenclature, but enables the site to address as many targets as is necessary.
The process takes a huge keyword universe of known target terms and organizes it into categories. The members of each category will be semantically related, sharing exactly matching terms with each other and the category target. The process is time consuming and arduous, but enables the building of a structure that focuses concentrated, target oriented semantics from these "power centers." Rather than relying exclusively on human navigation and contextual links, this implementation requires a contextual robot nav to deliver links into some of the power centers.
The principle of robot navigation is another unique aspect of structural optimization that enables the site to address targets that would not be appropriate for the traditional navs. For example, most product searches occur on both the singular and the plural term (widgets and widget). The traditional nav would never carry both - most likely the plural would be used. But if the singular term is strong enough to warrant its own power center, then the link to that power center must come from somewhere. Hence the usefulness of the robot nav.
Another very important aspect of structural seo is the manner in which the internal PR is passed back into the site. The power center structure permits PR to be distributed in ways that benefit both the long tails and the category level targets. Because of the aggregation of semantically related content in the power centers, and because the content of the related targets is interlinked (via robot navs), the long tail terms receive significantly more PR than they would if they were not part of the power centers. And conversely, all the urls addressing the long tail terms push PR back up to the category terms. Essentially, the PR cascades both ways from the homepage out to the long tails, and then back again. This means that when external links are pointing to category terms, the long tails receive juice, and vice versa.
So structural seo optimizes both the local implementation, that is, the semantics on the site, as well as optimizing the effectiveness of link building campaigns. Very simply, structural seo is an organizational strategy based on semantics that optimizes the site's overall viability in the search.