Using a simple method of estimating pace, we can estimate Offensive and Defensive Ratings for teams before 1974. Let’s start with Bill Russell’s famed Boston Celtic defense. Included is the year before he joined the team and the year after he left. The league rank also includes the number of teams (eg 1/8 is first of 8 teams).
(1) The Celtics led the league in defense in 12 of Russells’ 13 years.
(2) From 1958-1966 they dominated the league defensively like no team I can find for a 9 year period.
(3) From 1961-1965 the ran off 5 consecutive historically dominant seasons. Look at those numbers.
(4) Before Russell they were a bottom defensive team and immediately jumped 6.3 relative points and 8.0 raw points to the top.
(5) After Russell they dropped to the middle of the pack, losing 6.2 relative points and 10.1 raw points.
According to Neil’s method at B-R, who is slightly underestimating Boston’s pace relative to the simple method (because he’s assuming fewer turnovers are in play), those uber-dominant Celtics teams are the 3rd, 5th, 6th, 8th and 13th best defensive teams of all time, relative to competition. And there’s nothing remotely comparable in NBA history for such sustained defensive dominance.
Although this is just a cursory glance, deeper investigation supports the notion of Russell’s defensive prowess, both at USF, in Boston when he was injured, and his impact on the 1956 Olympic team.