Google Mobile algo traffic issue?

[McTaggart]

Hello, I have just been approach by a website owner - site isn't mobile friendly in any way - and they've seen a significant fall off in traffic since 23 Jan... backlink profile is clean (and no linkbuilding undertaken) - nothing else has changed... - more than half their traffic is via mobile devices and they've lost a good 1/3 of their traffic - and drilling deeper it's their organic traffic that's been hit. Anybody else seeing similar?

edit... for reference: https://www.davidnaylor.co.uk/google-released-mobile-algorithm-think.html

[McTaggart]

Thanks Ryan - have now checked and there is a message and the site is a disaster, from mobile perspective... oh dear me! I can see why Google is pushing mobile, though.

[RyanPurkey]

Hi Luke. Yes, Google has been putting an emphasis on improving mobile, especially from a UX perspective. As such I've seen sites get the following message in GWT:

Fix mobile usability issues found on example.com

Google systems have tested ### pages from your site and found that ##% of them have critical mobile usability errors. The errors on these ### pages severely affect how mobile users are able to experience your website. These pages will not be seen as mobile-friendly by Google Search, and will therefore be displayed and ranked appropriately for smartphone users.

If you have access to their GWT you'll likely find the same with further details on what needs improving. But this ranking drop is very much an official stance from Google and you can find several blogs discussing it, for example: http://www.vpdm.ca/mobile-friendly-websites-important-to-google/.