How useful are the Yoast Plugin SEO & Readability Scores?

By Simon Ensor
SEO 03.05.2019

Let’s get one thing straight. The Yoast SEO plug-in is one of, if not the most popular SEO plugin for WordPress websites. It’s been around since 2008. It has over 5 million installations and at the time of writing, a 4.9 out of 5 rating from over 26,000 reviews on

It’s really useful. We use it at Yellowball on a lot of our clients’ websites. The plugin allows webmasters to update meta data with consummate ease. We’d highly recommend using it!

However, there are some common misconceptions around Yoast’s SEO and readability score that we’d like to clear up. This isn’t based on us trying to pit our own SEO services against Yoast – they’re two different things. What we want to do is explain the benefits of Yoast, what the SEO and readability scores are, how they should be used and by whom.

Yoast does not ‘do’ SEO

The Yoast SEO plugin for WordPress helps you to implement key SEO items such as title tags, meta descriptions and the URL slug for the page. FYI the title tag is called the ‘SEO Title’ in the plugin. That is what the majority of SEOs use it for. You can navigate to each page on the CMS and change your meta data and slug in seconds. It also allows you to see when your meta data may be truncated – that’s when there isn’t enough space in the SERPs to see what you have typed. The character limits are really useful indicators for when you may need to review your meta data.

Yoast meta data
Using Yoast to input meta data and amend URL

Whilst these items are useful pieces of optimisation, installing the Yoast SEO plugin does not automatically mean that you are ‘doing’ SEO. You still have to manually input them and they make up only a small amount of an SEO strategy. It’s like buying a car and saying that you’re winning Formula 1 races, when in fact the car doesn’t have any fuel and you don’t have a licence. The plugin allows you to make changes to a portion of your site that could impact your rankings, but it doesn’t do it for you. Even if you do, you’ll need to do more than that to rank in even an averagely competitive industry.

Are Red Bullets bad? Do I need all my content to have green lights?

Yoast also offer some automated analysis of content, which is then fed back to the webmaster via a traffic light system. Green, amber and red. I don’t think we need to explain what the colours mean. They also split this out into SEO and Readability scores.

They’re called different things but most people refer to it as the green bullet, or the green light. You also have to remember that a lot of people who use Yoast are not SEO experts. These indicators can therefore be really valuable in providing indicative feedback to non-experts.

It becomes an issue when you start using these green bullets as the be-all and end-all of your SEO. As Yoast themselves say: “Don’t become a slave of the green bullet”. In fact, Yoast wrote a blog post that explains these bullets. I’ve included some of the quotes from the article below and you can read the whole article here:

“Don’t take them as gospel. They are tools, not commandments”

“Also, and this is the most important: never try to cheat the game by tinkering with your text until your red and amber bullets turn green”

“Use common sense to determine whether you can make improvements to your text”

“If all your bullets are green, that doesn’t mean you’ll rank”

We love Yoast’s openness in that blog post. It does a good job of explaining the benefits of the bullets and how to use them, and also addresses the common misconceptions. Still not convinced? Put it this way. If you paid a top lawyer to write a contract for you. Would you then tell them to re-write it because a free online tool says that the content isn’t good enough? You could use the tool to help write one yourself and it could be very helpful. But it’s highly highly unlikely to beat real human analysis.

SEO Score vs Readability Score

As mentioned, Yoast’s traffic light system delivers an SEO score and a separate readability score. Let’s have a quick dive into each one.

SEO Score

This is where it tends to fall down a bit. They released a new version of the SEO analysis in 2019 which looks at more than just meta data. It also looks at h1 tags, alt attributes, outbound links and more. However, one of the first items on the list is keyphrase density, otherwise known as keyword density. In order to assess your page you need to input your ‘focus keywords’ from which the tool will base its assessment.

Here’s the problem. Keyword density hasn’t been spoken about in the SEO industry for a rather long time. There is no magical number that you need to hit in order to rank. Sure, including exact match or phrase match keywords in meta data, headings and body copy where possible is beneficial. But it’s not everything. Google’s Hummingbird and Rankbrain updates provide them with the ability to understand the intent behind search terms rather than the individual keywords themselves. As such, including synonyms and what is known as semantically relevant content is also a powerful tactic. Maybe we’re biased because we’re an SEO agency. We do all of this research internally and implement where required; we don’t input any focus keywords because we don’t need to. However, we can see how it could be beneficial to those that are not experts in the industry and need a little guidance. Just don’t live and die by the SEO score. Create content for the user first. That’ll be by far your most effective strategy.

Readability Score

Yoast base their readability score on research that they conducted on 75 articles across the web. They also use Flesch reading ease score. Essentially it looks at creating sentences that are not overly complex or convoluted, they also advise on less complicated vocabulary. Whilst this usually reasonably good advice, it isn’t specific to your website. Some industries will naturally use more complex sentences and vocab, whereas others might suit this simpler style of writing.

For us, 75 articles isn’t a very large data set and as previously stated we’d always trust an expert over a free tool. Some of you may also use Hemingway App. Again, a useful tool in highlighting potential improvements, but don’t freak out if you can’t get a perfect score.

Yoast Analysis

Sometimes Yoast cannot read your content.

You also have to bear in mind how your website has been built and structured. If your web build was highly customised there can be instances where Yoast struggles to read the content. It therefore struggles to provide any analysis. As an example, our SEO page returns the following analysis:

Yoast analysis error

Apparently there is no text on the page. The reality is that we have a considerable amount of text on the page:

Screenshot YB SEO Page
Screenshot of text on page

In this case, if you were a die hard fanatic of the green light, you would probably cause a lot of unnecessary work. All of the content is available to the user and is indexed by the big G. That’s ultimately what this is all about.

Wait, so should I use the green, amber & red bullets or not?

Yes and no. If you’re unsure about what you need to be doing for SEO then it can be a useful tool. Always create the page content first, taking into account your buyer personas and sales funnels. Only then should you look at these scores and see if you can spot opportunities for improvement. Just don’t make your content worse in order to try and fit in ‘x’ percentage of keywords. That’s not how SEO works. Focus on providing value and relevance for the user. If you do nothing else, this will provide more results than getting a green light.

If you work in SEO hopefully you’re not basing your campaigns on Yoast’s SEO or readability scores. Hopefully you haven’t made it this far in the article. Who knows, you may have clients that you want to share this with in order to manage their expectations of the bullets!

Thanks for reading and I hope it was helpful.

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