The 1st ranked Thunder defense (102.7 drtg) is 6.9 points better than the 2nd ranked Pistons (109.6). This is the same difference as the Pistons and the 21st ranked Bucks.
Despite missing 22 games from their two All League defenders and a smattering of missed games from Chet Holmgren, Alex Caruso, and Cason Wallace the Thunder buzzsaw keeps humming along.
It’s early days yet, but the Thunder are currently 11.94 points better than league average. For context, last years league best Thunder d finished 6.92 points above avg, and the best defense of the play by play era, the ‘04 Spurs, were +8.5
Sources: defrtg - NBA stats - https://www.nba.com/stats/teams/advanced?dir=A&sort=DEF_RATING
relative def eff - pbpstats - https://www.pbpstats.com/relative-off-def-efficiency/nba