NBA Stats Explained: Offensive & Defensive Rating
A NBA teams net rating is more predictive of future in season success than a teams record. If your favorite team has a great start to the season, checking the teams net rating is a good way to see if it’s real or fake. But what is net rating?
Net Rating is a combination of a teams offensive rating vs their defensive rating.
Simply put, offensive rating is how many points does the team score every 100 possessions. Someone could also call this offensive efficiency or offensive production.
Per game or per possession. That is the key battle here. I need you to be aware of the flaws of per game stats as basketball teams play at different tempos or pace of play. Teams that play a faster tempo, run in transition, will play more possessions per game. More possessions per game = more shots per game = more points per game. Inversely, a team that slows the game down, plays more half court offense will have less possessions and by default less point per game.
To summarize, DO NOT use team points per game to indicate which NBA team has the best offense.
Let’s look at an example.
In 1991, if someone asked a fan which team has the better offense, Lakers or Nuggets? The fan would look at scoring per game, a stat that favors the Nuggets 120–106 and say the Nuggets are easily the better offense. They score 14 more points per game than the Lakers! Come on, no contest.
That fan was incorrect.
The Nuggets played at a much faster pace with 114 possessions per game, twenty more than the lakers. Let’s throw per game stats out the window. It’s the final play of game seven, one possession left, which team would you want for your offense? The Lakers scored 1.12 points per possession, while the Nuggets scored 1.05 points per possession. The Lakers may play at a slower place than the Nuggets, but the Lakers offense is superior. The Lakers score less points per game, but more points per possession as they play at a slower pace and their games have less possessions and fewer chances to score.
The Dallas Mavericks were the best offensive team in the 2019–20 NBA Season
With offensive rating we can see that the Mavs, Clippers, and Blazers had the best regular season offense, while the Bulls, Knicks, and Warriors had the worst regular season offense. (Never thought I would have to say the Warriors were the worst offense during a season in the Steph, Klay, Draymond era, but obviously they barely played any minutes this season.)
This is the same setup as above. The main difference is we are looking at how a team defends. The offensive rating of a teams opponents during play is considered defensive rating. How many points does this team get up per 100 possessions.
Again, we know per game stats don’t tell the whole story. This is why when looking at defense, do not use opponent points per game, use a teams defensive rating.
The Milwaukee Bucks had the best regular season defense in 2019–20.
Remember with defensive rating a lower number is desired. This is how many points a team gives up per 100 possessions. A good defense will give up less points than a bad defense.
The Bucks did a great job during the regular season playing their drop coverage. If opposing teams tried to attack the rim, Brook Lopez or Giannis were there to clean things up. This type of defense doesn’t work as well in the playoffs and it led to their demise.
We can use offensive rating to see how good a team is at offense.
We can use defensive rating to see how good a team is at defense.
Both those numbers are at a per 100 possession rate, so why not take the difference between a teams offense and defense and see their overall rating? Well, that is exactly what net rating is. We could also call it point differential.
The Milwaukee Bucks were the best regular season team.
After playing 100 possessions, the Bucks would be leading by ten points. They outscore their opponents by ten points every 100 possessions they play. That is all net rating is. The Chicago Bulls get outscored by three points per 100 possessions. The Warriors were the worst team as opponents would outscore the Warriors by ten points per 100 possessions.
Basically, I can look at this chart and see which teams are doing well (positive numbers) and what teams are doing poorly (negative numbers). If the Raptors started the season off with a poor record, but are +6 in point differential per 100 possessions like they are here, I could reasonably say that the Raptors are better than their record and should start collecting wins soon.
As the NBA season begins in about a month, make sure to use this stat to track if your team is actually performing well or not, regardless of their record.