The Philadelphia 76ers surrender 108.8 points per game, good for 25th in the league. Yet the NBA Stats for defensive rating shows the team at seventh at 103.7. How can we talk to such different stories?
The Philadelphia 76ers are a very complex NBA team. On one hand, this team is much improved over any other version in this decade. On the other hand, even improved, this team is very much an enigma. How good is this team? Is this team good? Is this team a playoff contender, or simply just a playoff pretender? So as any analytical process demands, the first step is to deep dive.
But deep dive where? At first glance, the game scores seem like a good starting point. From that vantage, the Philadelphia 76ers average 108.3 points per game of offense, while surrendering 108.8 points per game on defense. So that (0.5) PPG deficit on average translates into a 17-19 team record, and the sub-.500 performance so far. So far, so good. 108.3 points per game is good enough to rank seventh best in the NBA. 108.8 points per game is bad enough to rank as 25th in a 30 team basketball league.
So the problem is team defense. Or is it?
Defense combines denied scoring with opportunities to score
Well, there is the rub. The scoreboard tells one story. Basketball analytics tells another. So the first step is in understanding the use of dissimilar measures. The basic principal in any statistical analysis is the law of KISS. In short, keep it simple, stupid. In a measure of NBA defense, the ultimate and simplistic measure is the final score. If the other team scores more than you do, you need better offense or better defense. Or perhaps both.
The problem with comparing NBA teams is that different teams run the floor faster or slower than others. So one answer is to simply find a common denominator to compare these different teams.
Defensive rating
There is another school of though about these beloved Philadelphia 76ers. That camp believes that they play solid defense. And they have some statistics to back them up. On NBA.com/Stats , the defensive rating of the Philadelphia 76ers roster is 103.7, good for seventh best in the NBA. Now that is a different story altogether. Now there has to be something going on here, but what is it?
Well, it’s that fascinating field of Basketball Analytics, and how the efforts to create “like” comparisons sometimes do not achieve their goal. That may be the case with the use of Defensive Rating. In short, a team “defensive rating” is the number of points given up by a team per 100 possessions. Per Squared Statisics, the actual formula for any given NBA team’s defensive rating is the following (where TDR is Team Defensive Rating,)
The formula equals opponent points divided by team possessions multiplied by 100. Now here is where the kicker comes in.
PACE helps team defense, dilutes team offense
The Philadelphia 76ers have the second fastest team in the NBA. As of January 2, 2018, the team boasts the second fastest pace in the NBA at 103.34. The fastest team? The Los Angeles Lakers at 103.9. So what is pace? Pace is the average number of possessions per game for the team. The higher the number, the faster the team plays. So what?
Sir Charles In Charge
The use of Team Defensive Rating normalizes the effectiveness of all NBA teams by converting that into 100 possessions. That gives slow paced teams a bump on offense and a penalty on defense. Likewise, fast paced teams get a bump on defense and a penalty on offense. But why?
Slow teams better defense
Well, it does fall to reason that a slow paced team has lower scoring games, while fast paced teams score a ton of points. So a slow paced team like the San Antonio Spurs, which surrenders the fewest points, does so by limiting their opponents possessions.
Conversely, fast paced teams like the Los Angeles Lakers, surrending the most points by giving opponents far more possessions per game.
While the ultimate goal remains scoring more than opponents, rating attempts to neutralize the “PACE” variable in the comparison.
A practical example
The Philadelphia 76ers last defeated the Phoenix Suns 123 – 110. That is the raw score. But in terms of rating? Assuming the 103.34 average number of possessions in this game, the 76ers had a defensive rating of 106.4 and an offensive rating of 119.0 for that game. So which is the true number?
Air Alamo
Defensive rating is gaining in popularity as it attempts to create a comparable platform to use when rating players of different teams, different playing times, and different roles.
To that extent, it’s effective. It allows fans and analysts alike to judge the defensive impact of Joel Embiid, who has been limited in playing time and frequency, to a player like DeAndre Jordan, who typically plays every game in an NBA season.
How to use defensive rating
In the comparisons of dissimilar players, it’s a usefult tool in measuring whether a player has defense capability or not. But that utility of comparing teams begins to fade when you start comparing NBA teams.
The game scoreboard does a pretty good job of that already. If the opponent is scoring more points that your team, you need to improve your team’s defense.
Which answer is correct? Is the defense good or not?
This is where things get more complicated. In fact, let’s start with the term “good or bad” There actually is no definitive answer. But there are relative answers. The Philadelphia 76ers defense effectiveness is less than desired relative to the offense effectiveness. Wow. That’s a lot of big words trying to say the team struggles to score more than their opponent. And that is what the statistics are trying to measure. Is the defense effective?
But offensive or defensive rating can help focus the coaching staff attention on key factors to get the most bang for the buck. You see, if the team is sub-.500, which side of the ball needs more attention? If you look at the rote score, you will struggle to improve this team. You see, the Philadelphia 76ers run 103.34 possessions per game. That elevates the team’s points on both offense and defense. Since the team is second in the NBA in terms of pace, you should expect the offense to hover within the top-five and the defense to hover within the bottom-five.
Relativity, relative, and relatives
Defensively, the team is at 25. Now we have evidence that the 25th placed defense is better than expected. So what about the offense? An offense at 108.3, coming in at 7th best in the NBA, is now lower than expected when considering the pace at which that offense performs.
At the end of each game, we all turn to the score. If the 76ers do not outscore their opponent, then we turn to the points allowed in the game. If that number is over 104 points, it’s a safe bet that the first thought concludes the defense was horrid. But with a team that gels nearly 104 possessions per game (which is seven possessions more that a typical game for the San Antonio Spurs), there is 14 point potential for more points scored and given up. The Philadelphia 76ers need to outscore their opponents. While the scoreboard suggests the team simply doesn’t play good defense, the defensive rating suggest the 76ers play solid D.
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Which is more important for the team? You decide. But now you know why the values are so very different. And as a result, you can explain why those differences are both true.