Frank, it may seem that Post Kinds only works well with microformats, but this isn’t the case. It’s running some more sophisticated code based on Parse This which looks for microformats/HTML first and then it drops back to, JSON-LD, and then OGP metadata as a back up. When Post Kinds doesn’t find or return much data, it’s because the site is providing none of these.

If you’re finding posts that do have some sort of mark up, but aren’t parsing properly, ping David Shanske and let him know.