Many of the recent changes in Google's algorithm that are demoting and promoting certain results are based on thresholds. Recent major algorithm changes which seem to be threshold based include Panda (user metrics), PageLayout/Above the Fold Penalty (page content analysis), Over Optimization Penalty (Linking analysis).

Google, in their typical complete lack of openness in regards to their organic algorithms, does little to let you know where you are in regards to these algorithms). Although there have been some sites getting notices of links that look like paid links, they still don't tell you where you are in regards to the threshold.  And there has been no communications on Panda or Page Layout.

Think about this ... you could be knocking on the door of Panda, Page Layout Alog,  or Link Over Optimization, meaning you could be one content initiative, page redesign, link building initiative or other site change away from triggering a loss of 30%-80% of your organic revenue (which of course is the best type of revenue.)   How many businesses can survive that? Say the passing score for Panda is 65. You have site A with a score of 66 , fat, dumb and happy as a clam even though  they are teetering on the verge of a specific hit.

And then you have Site B, maybe they failed with a score of 64  lost 50 % of their traffic and they are firing people or shutting their doors. Yet they might be hanging right below the threshold, not much different from Site A. Doesn't see fair, does it? Site C might be well beyond repair and a truly crappy site but the impact on site B and C might be indistinguishable. 

So what is the poor SEO to do? We need to practice defensive SEO. We don't wait to get hit.  SEO is no longer about spewing out reems of content, at least without thought to site relevance, content quality and usability. In fact, good SEOs are going to be learning quickly to integrate search usability into their methodology. Bad SEOs are still going to be pushing out content and outsourcing link building with no regards to quality of links or spaminess of the techniques. As I mentioned when I first started this blog, good SEO has changed and should no longer be at odds with usability - rather it needs to be tightly integrated. We rarely get rewarded for saving traffic - but we need to do it anyway.