I don’t trust the defensive rating. What metrics for defense are to be trusted?
What Jamal said. Eye test + a few of the metrics he listed and you can usually get a good idea of a player's defense. It's easily the most difficult thing to analyze on the court and capture statistically.
There's always going to be outliers. A lot of the metrics really like TD for some reason. He gets a fair share of steals and is a good rebounder but he misses his assignments a lot. I'd grade him as an average to slightly below average defender from my eye test because he does some good work on that end of the court, it's just he mixes it in with a lot of brain farts.
A lot of times the stats will weight heavily in favor of a player who gets a lot of steals or blocks but steals can be a bit misleading because yeah they're a positive because you caused a turnover but how many gambles did you take or how often did you leave your man to play a passing lane and guessed wrong to get those steals? Many times the steal leaders in the league are among the worst defenders. Like Rondo when he played in Sac.