Or are they? The Sixers defensive rating has improved over the past four games (2 wins, 2 losses), but have they really performed better? We'll take a look after the jump.
The Sixers now rank 21st in the league in defensive efficiency, down from their low point of 29th about a week and a half ago. Sure signs of improvement, right? Well, that depends. Consider this, in their past four game, the Sixers played three of the worst offenses in the league. The Nets rank 30th, the Bobcats 29th and the Bulls 27th.
You'd expect the Sixers' season numbers to improve drastically against those teams, but at this point in the season, looking at the cumulative number really doesn't mean much, the sample size is so small, your efficiency rating is going to be skewed greatly by who you play. For example, playing against the Raptors, who lead the league in offensive efficiency at 114.5, a allowing a 104.5 rating in that game would really be a good defensive effort, while playing the Nets and allowing 104.5 would be atrocious. You really need to play a bunch of games before the cumulative number works out.
With that in mind, we have to look at who the Sixers have played, and how they've fared against the teams' season efficiency numbers (again, the sample sizes are too small, and can vary based who those teams have played, but it's a better barometer than your team's cumulative total). Here's the chart of the Sixers relative defensive efficiency vs. all the teams they've played thus far.
In 11 games, only three times have the Sixers held teams under their average offensive rating for the season, Milwaukee in the second game of the season (they actually held them almost 17 points under their season number), @ Detroit, barely, and @ the Nets, again barely. In the other 8 games, they've made opposing offenses look better, in six of those games, significantly so.
Obviously, you have matchups to consider, some teams will be better suited to take advantage of your weaknesses, etc, but you'd expect an average defensive team to cumulatively be pretty much even when you break their season down like this. Better defensive teams would have a positive DIF column, and a bad defensive team would be in the negatives. If you total up the DIF column for the Sixers, you get a whopping -76.14, or almost 7 points worse, per game.
The reasons are simple. A made three is the most-efficient offensive trip possible (with the exception of the four-point play, which almost never happens), the Sixers give up a ton of threes. Offensive rebounds extend possessions, so second-chance points kill you as well and don't show up in standard defensive stats, like field goal percentage (one possession could result in 3 shots, with only the third falling if there are two offensive rebounds. In the box score, this shows up as 33% from the floor, which you would think is great defense. In offensive rating, this is 2 points on one possession, which is pitiful).
In a nutshell, the Sixers "don't defend the three and don't worry about grabbing defensive rebounds" philosophy is creating a perfect storm of inefficient defense. It looks like they're only ranked as highly as 21st because they've played 7 of their 11 games against teams ranked in the bottom half of the league, and five of their games against four of the worst offensive teams in the league (Nets 30th, @ Nets 30th, @ Knicks 26th, @ Bulls 27th, Bobcats 29th). They were even in negatives against those teams, thanks in large part to the pitiful defensive effort they put forth in the Garden against the Knicks.
If this trend continues, and I don't really see any reason to think it will not, the Princeton offense is going to have to transform the Sixers from a mediocre offensive team (currently, the 21st most efficient offensive team), to a top-ten offense. Does anyone think that's possible?