this has been discussed to some extent here and somewhat here, but after reading an article that uses plays per game (wtf?) as a defensive metric, ive decided i still don't know defensive metrics/decided to make a fanpost on it.

let me sum up what i know about defensive metrics: i don't know shit. i've read that metrics are unreliable and inconclusive and there's no way to tell with any precision how good a certain player is defensively. which makes me wonder: how do we know that mark ellis is a premium player because of his defense?

so AN, i ask you: which defensive metric (if any) do i trust? i want all the information you have on the mysterious topic that is defense.