I've seen a fair amount of NBA writers mentioning Rondo's defense in a positive light as of late. I have always thought his defense is vastly overrated, as he gets lazy and often takes chances going for steals.
Could any wiser fans than I -- potentially ones with a grasp of advanced numbers -- let me know if this belief is merely conjecture or based in something more?
With the exception of this most recent season (which we can fairly exclude because he was coming off the ACL surgery), Rondo's defensive rating has been consistently above average. From 2007 through his ACL injury, his defensive rating was around 100. By means of comparison, KG's career average defensive rating is 99 (although his average during the Boston years is 97, and his DPoY season was an astounding 94). LeBron's career average is 102 (101 in Miami).
Now, defensive rating is not a perfect metric by any means. There is a lot of noise in that calculation; however, it is still noteworthy that by this metric Rondo is rated along with other good defensive players.
In terms of his raw numbers (that is, production per 36), Rondo is above average at getting steals as well as above average at avoiding fouls. That is, he gets more steals and fewer fouls per 36 minutes then the league average. This is a pattern you expect to see out of good defenders. Compare this with players like Brandon Jennings, who are above average at getting steals but ALSO above average at getting fouls; this is what you expect to see out of players that gamble themselves out of position and hack at the opposing player to try and make up for it.
That is, despite the grief some people subjectively assign to Rondo for gambling out of position on defense, the numbers seem to imply that this criticism is overblown, and Rondo is a positive on defense.
There is also the Revised Defensive Composite score (described in detail
here), which is a measure of standard deviation above positional averages based on on-court/off-court plus-minus splits and opponent PER. According to this measure (which is admittedly out of date, the only numbers I can find are from 2007-8), Rondo's score is 40.8, which ranks as "very good defender". By means of comparison, KG is 52.2, LeBron is also 40.8, Dwight is 37.3, Amare Stoudemire is 4.9, and Andrea Bargnani is -12.6.
The new player tracking data provided by the NBA has a plethora of other useful measures (such as opponent FGM at the rim, opponent FG% at the rim) but it is only available for this most recent season, which I don't think is a useful indicator of Rondo's overall defense. In fact, I can't even find Rondo's data on their rankings for this season. Next season, assuming he plays all year and returns to form, those numbers will be interesting.
