This is kind of surprising up until lately, I suppose. To the surprise of many followers, the Houston Rockets have been better defensively than offensively. It's resulted in no titles, but they've enjoyed tons of (at least) regular season success.
The Rockets have won 40-plus games in all but three seasons and have made the postseason on nine occasions. They are ninth offensively, with an effective field goal percentage of 49.55%, and sixth defensively.
As a byproduct, Houston ranks third in net rating (2.0) and fifth in nERD.