All season long, D-League.com will be looking at its top prospects and teams through the lens of advanced stats. Today, we break down the league so everyone's moving the same speed.
The Rio Grande Valley Vipers play at a pace far higher than most of the NBA D-League -- which creates some complications when you track their offensive and defensive abilities.
Jack Arent/NBAE via Getty Images
We've come a long way together. Now, let’s get back to basics.
Today, our focus will be on rate statistics, which – as a refresher – track different paces of play by charting teams and players over a specific number of possessions. There are many rate statistics floating around out there in the ether, but none more essential than these three: Offensive Rating (OffRtg), Defensive Rating (DefRtg) and Net Rating (NetRtg), a trio I like to call...
“The Holy Trinity of Rate Stats.”
Definition: The rate at which a player scores, compared to how often his team has the ball
(Pts produced / Indiv. Possessions) x 100
Definition: The number of points a team scores per 100 possessions
100 x Pts /
(Tm FGA + .04 x Tm FTA - 1.07 x (Tm ORB / (Tm ORB + Tm DRB)) x (Tm FGA - Tm FG) + Tm TO)
Individual ratings are easy. Teams, as you can see, are a little more complicated. So let’s start with an example.
The Bakersfield Jam are scoring 104.4 points per game, which ranks them fifth in the NBA D-League. However, are the Jam really the fifth-best offensive team? When you look a little deeper, you’ll see that the answer’s not that simple.
Most telling is the fact that the Jam have the second highest PACE (possessions per game) in the league, with a mark of 102.7. So, even though their raw scoring data ranks near the top of the league, that figure’s offset by the fact that they have the second-most opportunities to score. To account for this issue and put all the teams on the same playing field (or, rather, court), we use OffRtg, which measures points per 100 possessions, and can also be calculated for individual players. The data is as follows:
|Team-by-Team Offensive Rating|
|Rio Grande Valley Vipers||103.23||113.9||110.0|
|Los Angeles D-Fenders||97.73||104.8||107.0|
|Sioux Falls Skyforce||97.77||98.4||100.4|
|Fort Wayne Mad Ants||98.64||99.7||99.8|
|Maine Red Claws||98.21||97.4||99.3|
You’ll notice that when we rank the NBA D-League teams according to OffRtg, the Bakersfield Jam are 10th, a far cry from their stellar points per game ranking.
DefRtg = (Opp Pts Allows/ Opp Possessions) x 100
Much like the offensive side of the game, defensive ability cannot be measured by simply looking at how many points a particular team yields per game. It is for this reason that we use DefRtg, which measures points yielded per 100 possessions for both teams and individuals. A perfect illustration of the value of this statistic is the defensive ability of the RGV Vipers.
But this is a class, after all – so before I go into more detail about DefRtg, take a look at this data below and see if you can explain the measurement yourself.
|Team-by-Team Defensive Rating|
|Los Angeles D-Fenders||97.73||98.7||100.8|
|Maine Red Claws||98.21||101.8||103.6|
|Fort Wayne Mad Ants||98.64||103.0||104.1|
|Rio Grande Valley Vipers||103.23||107.5||104.5|
|Sioux Falls Skyforce||97.77||103.0||105.1|
You’ll notice that if we rank the teams based on opponent points per game, the RGV Vipers give up a league-worst 107.5 points. However, this statistic is misleading . Remember that Vipers have a league-high pace of 103.23, which means that their opponents are given more opportunities to score than against any other NBA D-League team. If we examine their DefRtg, we find out that they rank 11th in the league. Sure, it’s still not great, but it does tell a far different story than being ranked last.
Definition: The difference in how many points a team scores and gives up, per 100 possessions
NetRtg = OffRtg – DefRtg
Putting together Offensive Rating and Defensive Rating, we get Net Rating, which is calculated the following way:
Net rating measures scoring differential per 100 possessions is essentially used as a “+/-“ calculation that accounts for pace. Much like OffRtg and DefRtg, NetRtg can be calculated for either a team or individual. League NetRtg data is as follows:
|Net Ratings, NBA D-League Teams|
|Los Angeles D-Fenders||97.73||6.1||6.2|
|Rio Grande Valley Vipers||103.23||6.4||5.6|
|Maine Red Claws||98.21||-4.4||-4.3|
|Fort Wayne Mad Ants||98.64||-3.3||-4.3|
|Sioux Falls Skyforce||97.77||-4.6||-4.8|
Now that we have built a foundation with these three essential rate statistics, we will be able to perform deeper explorations of team and player stats and venture headlong into the world of on- and off-court data, which measures how a player’s presence on the floor impacts his team or other players. For a taste of that calculation – and a preview of what’s to come – check out our analysis of Walker Russell’s call-up last week.