And your “Zombie Pages” way is a really a PROVEN way. 15-20 days after getting hit badly by Broad Core Algorithm Update, I sorted out the least performing unnecessary articles (around 50% of total posts) from the blog and deleted them. Then, BOOM! Within 4-5 days, my search rankings and traffic got increased steadily day by day to get back where it was previously.

Hi Chris, "Good content" means a couple of things - good for readers and good for Google. Good content for readers means that the content answers questions, provides value, offers solutions, and is engaging. You want to keep the reader on the page and on your website for as long as possible. To make good content for Google, you have to provide the search engine with a set of signals - e.g., keywords, backlinks, low bounce rates, etc... The idea is that if you make good content for readers (engaging, valuable, actionable, and informative), your content will get more engagement. When your content gets more engagement Google will see it as good content too and put it higher in the SERPs. Making "good content" is about striking that balance. Let us know if that answered your question!
One of the things that can slow-bleed the traffic from your site is the quality (or lack thereof) of the content you publish on your site. Previous Google updates like Panda have already been released specifically to deal with the issue of low-quality content on websites. Long story short: Panda intended to stop sites with bad content from appearing in the search results.
Structured data21 is code that you can add to your sites' pages to describe your content to search engines, so they can better understand what's on your pages. Search engines can use this understanding to display your content in useful (and eye-catching!) ways in search results. That, in turn, can help you attract just the right kind of customers for your business.
Another good thing to look at is domain authority and core page authority. If your site has had a few redesigns, moved URLs, or anything like that, it’s important to make sure that the domain authority has carried over. It’s also important to look at the page authorities of your core pages. If these are much lower than when they were before the organic traffic slide, there’s a good chance your redirects weren’t done properly, and the page authority isn’t being carried over through those new domains.
Thanks for the comment Slava good too see your team is on top of things and happy you liked the post. The website in the case listed was a client who has taken on an agency who was doing lower quality SEO work which was affecting the site such as the huge link network and a strategy which only revolved around mainly head terms. We saw no long tail integration from the old agency's strategy, so we were able to yield great results to begin with. The clients site has 100's of high quality articles which we were able to re optimize and update as noted. Further to this they had a large index of high quality pages to work from. Sure enough the points listed above were key elements to a far wider strategy which could be 100's of points. I just wanted to include some of the biggest wins and easy to implement points.  
Having large groups of content that all revolve around the same topic will build more relevance around keywords that you're trying to rank for within these topics, and it makes it much easier for Google to associate your content with specific topics. Not only that, but it makes it much easier to interlink between your content, pushing more internal links through your website.
Brian, I have become a huge fan of yours over the last 3 months – I make it a point to read one of your articles every 2 weeks to help boost my Life & Career Coach website. Today I was reminded of a few points I had put off and will now implement (such as creating videos), and I learned cool new things such as LSI keywords and great tips about how to keep prospects longer on my site.
I have always believed in good quality content, well structured and written in a way that isn’t just about promotional talk. Thanks for sharing this information with us, it’s always helpful to have everything written in a concise manner so we can remind ourselves now and again of what it takes to increase organic traffic. As an SEO consultant myself I come across websites all the time that are messy and still using tactics that have long been out of date. Having a successful website is all about quality content and links. I like it that you stated what the problem was and then how you fixed it for the client. Great article.
I am too much late to commenting on this article. I want to read "How much get Organic traffic by SEO", found your your article on top & really very interesting. James Norquay, you did good research.I think Now days google block mostly SEO activities. Is this worthy for current marketing scnerio?If any other post to related strategy for increasing Organic traffic, you can reffer me.
Second and last, keywords. I use SEO Ultimate on WordPress and I sometimes doubt about what words and sentences to put in the “Tags” box. Does it need to be very specific or broad words are good to have too ? Like if I’m writing about Porsche beating the previous record on the Nurburgring with the new GT2 RS, can I put “Nurburgring” and “Porsche GT2 RS” as tags or is better to just keep “Porsche record nurburgring” and specific tags like this one ? How I Got a Ton Of Organic Traffic To a Local Website With 1 Blog Post