Looking into Bob's history as an assistant coach, his teams haven't been particularly good at defense. None have been bad, but over the past five seasons (2 years in Chicago with Vinny Del Negro, 2 years in Portland, and of course this year), they've never had a defensive rating better than 11th in the league, except for this year. So while I'm hesitant to give him all of the credit—I'm sure he's got loads of talent on his defensive team, including Ms. Nakase—I think that like Mike D'Antoni's offense and those memorable Phoenix teams, Ociepka's defense may have found its perfect fit with this team.
Watching the games this season, I've noticed one major difference from last year's 18th-ranked defense to this year's 3rd-ranked defense. The Clippers' defense on ball-handlers in pick-and-roll situations has been nothing short of brilliant. The combination of quick hands and quick feet by not only the Clipper guards, but also by the Clipper bigs, has resulted in a nightmare for all but the most elite point guards. And considering that the pick-and-roll is one of the staples of the NBA offensive diet, developing strong pick-and-roll defense would seem like a pretty quick path to success.
It was surprisingly easy for me to confirm my eye-test analysis of the defense. Ociepka's defensive philosophies are, as expected, heavily grounded in how to guard ball screens. A YouTube search for "Ociepka Defense" results in a great video about how to hedge on screens, naturally hosted by Ociepka. Further exhaustive research (i.e. Googling "Bob Ociepka Defense") resulted in an article written by Ociepka, describing in great depth the different ways to defend the pick-and-roll, shedding even more light onto his philosophies.
As mentioned earlier, this team appears to be the perfect fit for this sort of defense. Both Chris Paul and Eric Bledsoe are the perfect types of defenders (small, fast, strong) who can squeeze over screens as they do in the video. Simultaneously, the Clipper bigs have done a much better job this year of popping out and hedging on these screens, giving our guards time to go over the screen without letting the ball-handler turn the corner. All four of the Clipper bigs have really fast feet. Odom and Griffin, in particular, have extremely fast hands and shockingly have career highs in steal rates this year—it took Blake three years, but he seems to have figured out that he's less Dikembe Mutombo and more Gary Payton. He's the league leader among PF/C's in steals per game, and third (behind James Johnson and Andray Blatche) in steals per 36 minutes.
According to Synergy Sports Technology, the Clippers rank 3rd in the league in Pick & Roll defense, allowing just 0.77 points per possession (PPP). That's insanely good. For reference, here are some other teams (top 6 in defensive efficiency per ESPN):
(All of these numbers were taken from this really handy site, which is pretty awesome, and it's free. You can adjust the teams at the top.)
Overall, the Clippers' 3rd-ranked defense is allowing just 0.87 PPP, which was covered by Citizen FlyByKnight in this awesome article he wrote back in mid December. He wondered, at the time, whether this team was actually playing elite defense, or if it was just a result of small sample sizes. Well, almost a month later, while their PPP-allowed is higher than before, they've moved from 4th to 3rd in the rankings—this just indicates that the league is scoring more across the board. So far, they're still elite, and from what I can tell, it appears to be largely due to their pick-and-roll defense. The pick-and-roll makes up about 15% of plays ran against the Clips, which is the second-most-used play against them, and that makes defending it kind of a big deal.
The other prominent play is the spot-up jumper (19% of plays), where the Clippers are ranked 13th, allowing 0.96 PPP. This isn't a huge area of concern, as you usually want opponents shooting long jumpers, but the problem is that 58% of these spot-ups are three-pointers. While the Clippers' overall three-point defense isn't actually that bad (16th in the league, allowing 35.9% from deep), they do not defend the spot-up-three very well at all, allowing an unappealing 38.7%. For reference, the top 2 teams at defending the spot-up are Indiana(1) and Chicago(2), who allow just 30% and 34.5% from the spot-up-three respectively (the bottom 2 are Phoenix(29) and Utah(30), allowing 43.2% and 43.9% from the spot-up-three respectively). So yea, the Clippers could be better at defending the spot-up-three, but it doesn't really seem to be hurting them much.
Having your opponents' most frequent offensive play be the spot-up jumper is a pretty good recipe for success. You can't feasibly defend every shot, so you have to pick your poison—for example, Indiana and Chicago are weak at defending the P&R ball-handler—and if you have to live with something, long jump shots would be the way to go. This would appear to be the strategy that Ociepka and his defensive team are taking with the Clippers. Harass ball-handlers, defend the pick-and-roll, and protect the paint. If teams keep playing into the Clippers' hands, I see no reason why they won't continue to be an elite defensive team by the end of the season.