Yoast SEO plugin in and Google rankings

My first PP site was really well ranked with the search engines. Over the years Google’s algorithm changes HAVE affected SEO.

I am really noticing that the Hummingbird changes are affecting how I build pages.

The YOAST plug in gives an SEO check but it seems redundant now that page titles need to be shorter, keywords are not so important etc.

Has anyone noticed a decline in their results using YOAST or perhaps I have to re-learn SEO.