Honest question did you ever watch the NBA in the 80s those Pistons defenses were ridiculous not to mention the Celtics, in the 60s era Celtics defenses were easily the best of all time not even a question . Nobody considers those bulls defenses as a top defenseive team of all time. They weren't even the best defense of their era.Those are all good defenses. That Bulls team had 3 first team All NBA defenders for that year. Though I have seen some other team defensive stats that show other defenses as better compared to their era, so the stats probably don't back my claim.