Google Ranking Tags?

I have a site in which Google is mainly ranking the tags using this theme.

like http://www.randomwebsite.com/subject/tag.

This means that the title displays in google as “subject tag archives” and when you click on it a search page comes up on my site with the pages that have those tags.

Strangely enough few of my real posts are ranking, only the tags and search-result-type-pages.

This isn’t my first niche website and I’ve never had this “problem”… so I was curious if it might have something to do with the Customizer theme? Like if for some reason Google favors the way the tags are in the theme?

The strange thing is the tags are often the same name as at least one page/post name.

For instance, a page will be “random subjects on my website” and the tag will be “random subjects on my website” plus a bunch of other tags…and yet the tag will rank, but the page/post wont.

My on-page SEO is basically just Yoast SEO plugin. When using it I make sure all of the green bubbles are filled in.

Could the theme be part of the reason the tags are ranking before (or instead of)the pages/posts? Or could it be my on-page SEO (Yoast)?

I’m glad something is ranking, but trying to figure out why Google is favoring the tags.

Also, I do have Google Webmaster and I’ve put sitemaps on there using the Yoast sitemap urls… including the site map for the tags if that information is relevant.

Thanks!