12/10/18 NBA Computer Ratings

Primer on my NBA Computer Ratings:

Like most other ratings of mine, my NBA Ratings follow an Earned Ranking method rather than a predictive ranking method. By this I mean, its goal is to rank teams according to their past performance in the season. Unlike many other earned ranking systems, I do not ignore scoring margin completely.  The ratings that follow give you a look into how good teams have been in the season thus far based on their wins and losses, the strength of teams played, and how dominant they have been.  There are 3 components.

 

Component 1: W-L%

This is simply (Wins/Total Games Played)

 

Component #2: SOS

The strength of schedule component is calculated simply:

((2/3 opponent’s W-L%) + (1/3 opponent’s opponent’s W-L%)) * 1.5

The 1.5 coefficient exists in order to assign more importance and deviation in a team’s strength of schedule, as there is naturally not a huge variation in aggregate Opponent’s w-L% in the NBA.

 

Component #3: Schedule Adjusted Net Rating

The idea of offensive and defensive ratings have become more and more commonplace in the NBA world.  It boils down to points scored per 100 possessions (offensive rating) and points allowed per 100 possessions (defensive rating). I acquire these ratings from basketballreference.com. The net rating (Off Rat-Def Rating) is calculated then using an iterative process is adjusted for the average ratings of the team’s played.

Here are the formulas commonly used for offensive and defensive rating:

Offensive Rating: 100 x Pts / (0.5 * ((Tm FGA + 0.4 * Tm FTA – 1.07 * (Tm ORB / (Tm ORB + Opp DRB)) * (Tm FGA – Tm FG) + Tm TOV) + (Opp FGA + 0.4 * Opp FTA – 1.07 * (Opp ORB / (Opp ORB + Tm DRB)) * (Opp FGA – Opp FG) + Opp TOV)))

Defensive Rating: Follows the same formula but instead of 100 x Pts its 100 x Opponent’s points.

The ratings are calculated then their opponent’s average net rating is added or subtracted to it, numerous times until they converge within an iterative process.

Comp #3 Formula= (Adjusted Net Rating) * .8

The .8 is to account for the great variation in net ratings within the league as well as to prevent a team who is running the score up to gain a higher rating.

 

These 3 components are then averaged and multiplied by a 100 to give the rating.

 

12/9/18 NBA Power Ratings:

1. Toronto Raptors 21-7 51.70
2. Milwaukee Bucks 17-8 51.50
3. Denver Nuggets 17-9 48.78
4. Golden State Warriors 18-9 48.20
5. Los Angeles Clippers 16-9 47.90
6. Philadelphia 76ers 18-9 47.33
7. Oklahoma City Thunder 16-8 46.58
8. Portland Trail Blazers 15-11 46.14
9. Boston Celtics 15-10 46.06
10. Memphis Grizzlies 15-10 45.92
11. Los Angeles Lakers 16-10 45.64
12. Indiana Pacers 16-10 44.90
13. Utah Jazz 13-14 43.16
14. Sacramento Kings 13-12 43.10
15. Minnesota Timberwolves 13-13 42.77
16. Dallas Mavericks 13-11 42.56
17. New Orleans Pelicans: 14-14 42.52
18. Charlotte Hornets: 13-13 41.57
19. Detroit Pistons: 13-11 41.25
20. San Antonio Spurs 13-14 40.98
21. Orlando Magic 12-14 40.80
22. Houston Rockets 11-14 3.39
23. Miami Heat 11-14 37.57
24. Washington Wizards 11-15 37.39
25. Brooklyn Nets  10-18 35.67
26. New York Knicks 8-20 32.68
27. Cleveland Cavaliers 6-20 30.30
28. Atlanta Hawks 6-20 30.16
29. Chicago Bulls 6-21 29.75
30. Phoenix Suns 4-22  29.22