Saturday, April 21, 2012

NBA Team Rankings - April 21, 2012


Tank primeaguerra
World War I Tank
Here are the NBA Betting Market Team Rankings as of April 21, 2012. These rankings use the Vegas point spreads from recent games to derive an implied measure of team strength (Generic Points Favored, or GPF).  By combining the point spread information with the betting over/unders, I can also decompose team strength into its offensive and defensive components (oGPF and dGPF). For more detail, see the Methodology page.


At this point in the season, it's hard to say exactly what these rankings are telling us. Are the Thunder and Spurs really that much better than the Heat and Bulls?  How much are the point spreads affected by teams resting up for the playoffs?  Are teams that are out of the playoffs "tanking" in the hopes of getting a better lottery pick in the draft?  Or do they simply not try as hard at this point?


You could use the rankings below as indirect evidence of "tanking" (or rather that the betting market is expecting tanking). There are currently 11 teams eliminated from playoff contention. Not coincidentally, those 11 teams occupy the bottom 11 spots in these rankings. And if you look at the actual GPF's of those teams, there is a noticeable drop-off in strength. Such a result would be consistent with teams giving up once they are eliminated from playoff contention.


The Rankings (glossary below)

Rank Team LstWk GPF oGPF dGPF GOU W-L GWP
1  OKC 1 8.5 7.0 2 1.5 13 200 7 46-17 3 0.79
2  SAS 3 8.5 8.5 1 0.0 16 203 4 46-16 2 0.78
3  MIA 4 5.0 1.5 10 3.5 6 192 20 45-17 4 0.69
4  CHI 2 5.0 -2.5 21 7.5 1 185 30 47-16 1 0.68
5  MEM 7 4.5 -1.0 18 5.5 3 188 25 38-25 8 0.67
6  ATL 9 4.0 0.5 14 3.5 7 192 21 38-25 9 0.66
7  LAC 5 4.0 -0.5 16 4.5 5 190 24 39-24 7 0.64
8  UTA 18 3.5 3.5 7 0.0 18 198 9 33-30 15 0.63
9  DAL 8 3.0 0.5 13 2.5 9 193 18 36-28 12 0.61
10  IND 12 2.5 1.5 9 1.0 15 195 14 41-22 5 0.60
11  LAL 10 2.5 1.0 11 1.5 11 194 17 40-24 6 0.60
12  PHX 13 2.5 4.5 5 -2.0 20 201 6 33-30 14 0.60
13  BOS 6 2.5 -3.5 26 6.0 2 185 29 37-27 11 0.59
14  PHI 11 2.0 -3.0 23 5.0 4 187 27 32-30 17 0.58
15  NYK 15 2.0 0.5 12 1.5 14 194 16 33-30 16 0.58
16  HOU 14 2.0 2.0 8 0.0 17 196 11 32-31 18 0.57
17  DEN 17 2.0 6.0 4 -4.0 25 205 3 34-28 13 0.57
18  MIL 16 1.0 6.0 3 -5.0 28 206 2 29-33 19 0.53
19  ORL 19 -1.0 -2.5 22 1.5 12 190 23 36-26 10 0.47
20  NOH 26 -3.5 -5.5 28 2.0 8 187 28 20-43 27 0.37
21  POR 20 -4.0 -1.5 19 -2.5 21 196 12 28-35 20 0.36
22  TOR 23 -4.0 -6.0 29 2.0 10 187 26 22-41 24 0.35
23  SAC 21 -4.0 4.0 6 -8.0 30 206 1 20-43 28 0.35
24  DET 22 -4.5 -3.5 25 -1.0 19 192 19 23-40 22 0.34
25  MIN 24 -5.0 -0.5 17 -4.5 27 199 8 26-38 21 0.31
26  GSW 25 -6.0 0.5 15 -6.5 29 202 5 22-40 23 0.28
27  WAS 28 -6.0 -2.0 20 -4.0 24 197 10 16-46 29 0.28
28  NJN 27 -6.5 -3.0 24 -3.5 22 195 13 22-41 25 0.26
29  CLE 29 -9.0 -4.5 27 -4.5 26 194 15 21-41 26 0.20
30  CHA 30 -11.5 -7.5 30 -4.0 23 191 22 7-55 30 0.14

GLOSSARY




  • LstWk - The BTM ranking from last week.
  • GPF - Stands for "Generic Points Favored".  It's what you would expect the 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).
  • GOU - Stands for "Generic Over/Under".  It's what you would expect the betting over/under to be for the given team when playing a league average opponent.
  • W-L - The team's win/loss record (and win percentage rank)
  • GWP - Stands for "Generic Win Probability".  I converted the GPF into a win probability using the following formula: 1/(1 + exp(-GPF/6.5)).

  • Additional Key Factors:
    • League Average Points Scored (APS): 97.0 points
    • Home Court Advantage (HCA): 3.25 points
    • Back to Back Penalty (B2B): -1.25 points (see here)
    How to Use This Table to Build Point Spreads and Over/Unders
    • Point Spread (in favor of home team) = HCA  + (B2Bhome - B2Baway) + (GPFhome - GPFaway)
    • Over/Under = 2*APS + (oGPFhome + oGPFaway - dGPFhome - dGPFaway)

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