I consume my feeds at a folder level rather than the individual feed level, some feeds contain a large number of posts.
It would be great if in the same way you display dead feeds you could display feeds where I rarely view the content (other than scanning through the headings).

For example on feed Y tell me that I only expanded or visited 2% of the posts.

This feature would be useful where you have multiple related feeds to ensure a wide converge and want to flag up and remove those sources which are not as good.