I could maybe get behind a site explaining police ranks by their country / guide to rank structure. In that respect, I'd be a bit happier with "police rank" (or ranks). Struggle with the reverse. Comes across a different way, like literally ranking the police on their conduct, behaviour or efficiency, than their position in the force. Even with that line of thinking, if you have a problem with the police, you wouldn't go to some ranking site (would be reported in a different way)