Our best defensive unit? According the basketball reference, here is the top-10 defensive ratings for the entire league:
1. Hassan Whiteside MIA 94.4
2. Terry Rozier BOS 96.6
3. Aron Baynes BOS 96.8
4. Al Horford BOS 96.8
5. Kyrie Irving BOS 96.9
6. Marcus Smart BOS 97.0
7. Jaylen Brown BOS 97.2
8. Ed Davis POR 97.3
9. Jayson Tatum BOS 97.7
10. Andre Drummond DET 98.3
https://www.basketball-reference.com/leagues/NBA_2018_leaders.html
I find these leader stats to be remarkable. CBS is a great coach.
While it's clear that the Celts have an elite defense (and a great coach), I think these stats speak just as much to how crude defensive stats are still -- very poor at distinguishing an individual's contributions to a strong unit's defense.
I agree and disagree. This season could be an utter outlier for the defensive rating, but typically there are few on the same team on the top 10 list, and if they are, the team is a top defensive team.
Because the defensive rating typically does a decent job, it seems better that we should recognize that this team has really been that elite on defense, especially in comparison to the current rest of the league.
However, it is definitely an incomplete stat. I like seeing player tracking stats to see what kind of percentages defenders are holding offensive players to. Although that is an incomplete stat also, it is a primarily individual stat.
Combine the two, and great defenders are at the cross-section.