Wednesday, January 11, 2012

NBA Team Rankings - January 11, 2012


Here are the NBA Betting Market (BTM) Power Rankings as of Wednesday, January 11, 2012.  I plan on updating these on a weekly basis, probably around Wednesday or Thursday (I'm trying to find the optimum time and day for updates that catches both the Wednesday and Friday games).


The general idea behind the rankings is to use the point spreads and over/unders for recent games (the past three weeks) to derive a power ranking, with more weight given to more recent games.  There is also an adjustment that accounts for actual game outcomes.  Refer to the Methodology page and my post at Advanced NFL Stats Community for more detail.

Glossary

Here is a glossary of terms used in the rankings table below (the structure of the table and the metrics shown draws significant inspiration from the Advanced NFL Stats Team Efficiency Rankings):

  • GPF - Stands for "Generic Points Favored".  It's what you would expect a team to be favored by against a league average opponent at a neutral site.
  • oGPF - Stands for "Offensive Generic Points Favored".  The component of a team's total GPF attributable to its ability to score points (per game).
  • dGPF - Stands for "Defensive Generic Points Favored".  The component of a team's total GPF attributable to its ability to prevent the other team from scoring points (per game).
  • GWP - Stands for "Generic Win Probability".  I converted the GPF into a win probability using the following formula: 1/(1 + exp(-GPF/6.5)).
  • oRANK - The team's oGPF ranking.
  • dRANK - The team's dGPF ranking.



The BTM Rankings:


RANK TEAM GPF oGPF dGPF GWP oRANK dRANK
1 Heat 8.0 7.5 0.5 0.77 1 15
2 Bulls 7.0 1.0 6.0 0.75 12 1
3 Thunder 6.0 6.0 0.0 0.71 3 17
4 Seventysixers 4.0 2.0 2.0 0.65 9 7
5 Trailblazers 4.0 2.0 2.0 0.64 8 8
6 Spurs 3.5 3.0 0.5 0.63 6 13
7 Magic 3.0 0.0 3.0 0.62 14 5
8 Nuggets 3.0 7.0 -4.0 0.62 2 29
9 Lakers 3.0 -0.5 3.5 0.61 17 3
10 Clippers 3.0 5.0 -2.0 0.60 5 21
11 Mavericks 2.5 1.0 1.5 0.60 13 10
12 Celtics 2.5 -1.5 4.0 0.59 20 2
13 Hawks 2.0 -1.0 3.0 0.58 18 4
14 Knicks 1.5 5.0 -3.5 0.56 4 26
15 Pacers 1.5 0.0 1.5 0.55 15 11
16 Grizzlies 0.0 -1.5 1.5 0.50 21 12
17 Suns -0.5 1.5 -2.0 0.48 10 22
18 Rockets -1.0 2.0 -3.0 0.46 7 25
19 Bucks -1.5 -3.5 2.0 0.44 24 9
20 Timberwolves -2.5 1.5 -4.0 0.41 11 28
21 Jazz -2.5 -2.0 -0.5 0.40 22 19
22 Warriors -3.0 -2.0 -1.0 0.39 23 20
23 Raptors -4.0 -4.0 0.0 0.35 27 16
24 Hornets -4.5 -7.5 3.0 0.33 30 6
25 Cavaliers -4.5 -1.5 -3.0 0.33 19 27
26 Kings -5.5 -0.5 -5.0 0.30 16 30
27 Pistons -5.5 -6.0 0.5 0.29 29 14
28 Bobcats -6.0 -3.5 -2.5 0.29 25 23
29 Nets -6.0 -5.5 -0.5 0.28 28 18
30 Wizards -6.5 -4.0 -2.5 0.27 26 24

Additional Key Factors:
  • League Average Points Scored (APS): 95.0 points
  • Home Court Advantage (HCA): 3.5 points

How to Use This Table to Build Point Spreads and Over/Unders

  • Point Spread (in favor of home team) = HCA + (GPFhome - GPFaway)
  • Over/Under = 2*APS + (oGPFhome + oGPFaway - dGPFhome - dGPFaway)

For example, the Knicks play the Thunder at Oklahoma City on Saturday.  According to the ranking table above, here is the predicted point spread and over/under:

  • Point Spread (in favor of OKC) = 8.0 points (= 3.5 + 6.0 - 1.5 )
  • Over/Under = 204.5 points ( = 2*95 + 6.0 + 5.0 - 0.0 - (-3.5) )

My goal here is transparency, so if there are any questions on these rankings or the methodology, please comment.