westbrook is a scoring point guard like rose. that makes it even worse that he leads the league in turnovers because it means that he probably has a poor turnover to assist ratio. I don't know the number so I could be wrong. But i'm certain that nash typically has more assists than turnovers which is where a PG should be judged.
OKC is improving their defense and they have some big guys that can't score to save their life, but can block shots and rebound the ball.
The top 5 including Nash all have more assists versus turnovers. Nash has the best ratio among them. What I am saying is if you look at the overall performance of those teams a good defensive team can afford more turnovers than a bad one.