The matcher will only test if the content type has a field with the configured name, but will not test if the rendered field is the configured one.

Furthermore, the documentation is incorrect. It says to use Identifier\FieldDefinition for the matcher's key, while it is necessary to use to service's id:

content_query_field:
    blog_posts:
        match:
            Identifier\ContentType: blog
            '@EzSystems\EzPlatformQueryFieldType\eZ\ContentView\FieldDefinitionIdentifierMatcher': posts
        template: "@ezdesign/content_query/blog_posts.html.twig"