Just to expand upon this -
The closest (and somewhat close) teams that had such positions on offense and defense in the regular season (Spurs are ranked 3 and 12 respectively this season so far) and won a championship are -
Lakers (2000-01) - Offensive Ranking 2, Defensive Ranking 21
Lakers (1979-80) - Offensive Ranking 1, Defensive Ranking 9
Lakers (1987-88) - Offensive Ranking 2, Defensive Ranking 9
Lakers (1981-82) - Offensive Ranking 2, Defensive Ranking 10
Bulls (1990-91) - Offensive Ranking 1, Defensive Ranking 7
Lakers (1984-85) - Offensive Ranking 1, Defensive Ranking 7
Lakers (1986-87) - Offensive Ranking 1, Defensive Ranking 7
Lakers (2001-02) - Offensive Ranking 2, Defensive Ranking 7
Bulls (1992-93) - Offensive Ranking 2, Defensive Ranking 7
Rockets (1994-95) - Offensive Ranking 7, Defensive Ranking 12
Heat (2005-06) - Offensive Ranking 7, Defensive Ranking 10
Mavs (2010-11) - Offensive Ranking 8, Defensive Ranking 8
Bullets (1977-78) - Offensive Ranking 10, Defensive Ranking 9
I did this exercise only till 1978 (retrospectively).
In a nuts , the Showtime Lakers and the Kobe-Shaq era was the only teams that managed to win despite a just above average (or below average in the case of 00-01 team) defense (atleast in the regular season).