And, D.o.s,
As far as the defense thing goes; if you want to make the claim that Westbrook's better DRtg for this season makes him a better overall defensive player than Rondo, or, more importantly, assures that he will be a better defensive player going forward, then go ahead.
It's flimsy, though. I'm sure you are aware of that. Using statistics to try to determine who is a better offensive player is difficult enough (as this thread has contributed to proving), but trying to do it for defense is even hazier.
It's why I actually put a lot of weight into the All Defense awards. Unlike the other major awards, it is voted on by the coaches. I kind of trust the coaches who have to game plan against the other team to be the best judges out there of who makes the largest defensive impact on games.
Up until his knee injury, the coaches consistently chose Rajon Rondo as one of the best defensive guards in the league.
To me, that's the most significant piece of evidence for Rondo being an elite defensive player--other than, of course, my own eye test, which I realize that many will find unreliable.