The Old Penalty Paradigm: Compliance
You may not realize this, but the search results of Google were once corrupted by sites that had gamed the search, not through relevancy, but by exploiting weaknesses in Google's algorithm. To reclaim and protect the integrity of the search going forward, Google's now well known updates started enforcing strict compliance guidelines by penalizing the non-compliant websites. The previous algorithm adjustments and the introduction of stand-alone updates addressed flaws or oversights in the original algorithm that were being exploited by seos - Exact Match, Unnatural Links, Penguin, Panda, Payday Loans, Pirate, and many others unnamed. And with each update, the compliance requirements became more rigorous.
The New Rules Of Engagement
But starting with Panda 4+, there appear to be new standards that high ranking sites need to meet, in addition to all the existing compliance protocols. The old model required adherence to very clear guidelines, and all those rules still apply, but we're discovering that the focus of the latest updates is more on an evaluation of content presentation and user experience than on relevancy. Sites are recovering from Panda by altering the way the content is implemented, not by optimizing the content itself. You may be surprised to find that the same content ranks higher when presented differently.
Is There A Reliable Signal We Can Use To Gauge The Effectiveness Of Revisions?
Clearly, if you've lost your ranks to Panda, you need to improve your site. Content issues take a long time to remedy, so you may not receive the same kind of relatively quick gratification as you can from remedying other penalties.
Unlike the old penalties, where the problem was obvious to find and fix - bad links, keyword stuffing, duplicate/non-original content - the new standards require an examination of the overall presentation, including layout, images, media, page specific navigation, reviews, references, citation, etc. Other than seeing your ranks improve, how can you measure success?
Many seos believe that the metric to watch is bounce rate, since that measures the failure of a page to engage. While bounce rate is an unlikely ranking factor by itself, the idea that it's related inversely to engagement is spot on and useful, since we have seen that improving engagement is one of the solutions. Lowering the bounce rate clearly demonstrates better engagement. In addition, Google has already developed the technology to evaluate and measure engagement potential and uses it to rank Adwords ads. Panda may already be tapping into this technology and applying it to the natural search. In Adwords, your ads are rated 1-10, based on bid and quality score (engagement factors) applied to the ad text, the landing page, etc. High rated ads are cheaper and display higher than low rated ads - basically the organic rank for ads.
The penalty recovery evidence supports this view. Pandalized sites recover by focusing improvements on content presentation and on providing more appropriate opportunities for the user to engage. Exactly the ingredients that drive successful ads.
Content Is Still King - If It's Presented Properly.
Here are some of the very simple rules we use for content creation and to remediate Panda issues. Note that most of these efforts do not change the actual content.
Thin content is a negative engagement signal
Pages with little content should be made more robust (450+ words) or tagged noindex.
Use formal markup structure - use tags, image alt, links, titles, canonicals, schema.org, etc.
Engage with original media - images, charts, tables, video, etc. - use helpful alt and title markup.
Engage with interactivity
Post reviews, curated comments, tools, specialized search
Display personalized content options related to user/visit/session, forms, etc.
Engage with layout - make content easy to access and enjoyable to read - use white space.
Break up long text passages with supporting media.
Offer opportunities to visit related internal pages via contextual links or a page specific nav.
Cite sources. If appropriate, link out to authoritative sources to support or clarify your content.
Fix dead ends - always provide additional link options specific to the page.
Whether from Adwords or a parallel universe, It seems clear that some form of rating system is now in play, where instead of directly penalizing sites, a pecking order is established from the engagement metrics, and that information is now an influencer in the organic search.
Clearly Google is looking to advantage sites that offer a better user experience. So in the future, observed rank loss might be those unnatural links, or the loss of content authority, or a domain level issue... or the result of a low "engagement" rating.
More information on penalties in general is here.