Killboard wrote:As we always mention BKref ratings are not team based or take into account how the team perfomed when those players were on the floor, they are estimated based on how they performed on the individual possessions used. NBA.com has total different ratings and IMO are much better weighting the impact that a player had in the game for his whole team.
As we always mention BKref ratings are not team based or take into account how the team perfomed when those players were on the floor, they are estimated based on how they performed on the individual possessions used. NBA.com has total different ratings and IMO are much better weighting the impact that a player had in the game for his whole team.
Deng +10
Roco +3
KAT +1.4
Rose +1
Tyus +0.6
Teague -0.2
Okogie -0.6
Wiggins -0.9
Saric -1.3
Gibson -2
Dieng -2.2
Tolliver -3.9
KBD -5.6
Butler -8.1
BBRef's numbers are based off what the team does and ALSO takes in consideration what the individual player contributes, this is why Wiggins is so bad on BBREF (low TS%, bad defense) and why it's mitigated on NBA.COM because he's basically carried by his teammates to a better overall number(and why Town's rating on NBA.COM is so much worse).
NBA.Com's calculation is this...
100*((Points)/(POSS)
That's it... all the points and possessions while a player is on the court, doesn't matter if Towns is carrying you or J.Crawford is pulling you down, it's why Wiggins is only 2.3 difference from Towns and almost all of us can agree the divide is by far greater than that.
Since probably nobody goes to look at the way BBREF is calculated, I'll post the ORTG calculation here.
BTW... Oliver Dean's wikipeia(who came up with the formulas that bbref uses).
https://en.wikipedia.org/wiki/Dean_Oliver_(statistician)
Offensive Rating
In Dean's words, "Individual offensive rating is the number of points produced by a player per hundred total individual possessions. In other words, 'How many points is a player likely to generate when he tries?'"
The basic building blocks of the Offensive Rating calculation are Individual Total Possessions and Individual Points Produced. The formula for Total Possessions is broken down into four components: Scoring Possessions, Missed FG Possessions, Missed FT Possessions, and Turnovers.
The Scoring Possessions formula is by far the most complex:
ScPoss = (FG_Part + AST_Part + FT_Part) * (1 - (Team_ORB / Team_Scoring_Poss) * Team_ORB_Weight * Team_Play%) + ORB_Part
where:
FG_Part = FGM * (1 - 0.5 * ((PTS - FTM) / (2 * FGA)) * qAST)
qAST = ((MP / (Team_MP / 5)) * (1.14 * ((Team_AST - AST) / Team_FGM))) + ((((Team_AST / Team_MP) * MP * 5 - AST) / ((Team_FGM / Team_MP) * MP * 5 - FGM)) * (1 - (MP / (Team_MP / 5))))
AST_Part = 0.5 * (((Team_PTS - Team_FTM) - (PTS - FTM)) / (2 * (Team_FGA - FGA))) * AST
FT_Part = (1-(1-(FTM/FTA))^2)*0.4*FTA
Team_Scoring_Poss = Team_FGM + (1 - (1 - (Team_FTM / Team_FTA))^2) * Team_FTA * 0.4
Team_ORB_Weight = ((1 - Team_ORB%) * Team_Play%) / ((1 - Team_ORB%) * Team_Play% + Team_ORB% * (1 - Team_Play%))
Team_ORB% = Team_ORB / (Team_ORB + (Opponent_TRB - Opponent_ORB))
Team_Play% = Team_Scoring_Poss / (Team_FGA + Team_FTA * 0.4 + Team_TOV)
ORB_Part = ORB * Team_ORB_Weight * Team_Play%
Missed FG and Missed FT Possessions are calculated as follows:
FGxPoss = (FGA - FGM) * (1 - 1.07 * Team_ORB%)
FTxPoss = ((1 - (FTM / FTA))^2) * 0.4 * FTA
Total Possessions are then computed like so:
TotPoss = ScPoss + FGxPoss + FTxPoss + TOV
Now, Individual Points Produced must also be calculated:
PProd = (PProd_FG_Part + PProd_AST_Part + FTM) * (1 - (Team_ORB / Team_Scoring_Poss) * Team_ORB_Weight * Team_Play%) + PProd_ORB_Part
where:
PProd_FG_Part = 2 * (FGM + 0.5 * 3PM) * (1 - 0.5 * ((PTS - FTM) / (2 * FGA)) * qAST)
PProd_AST_Part = 2 * ((Team_FGM - FGM + 0.5 * (Team_3PM - 3PM)) / (Team_FGM - FGM)) * 0.5 * (((Team_PTS - Team_FTM) - (PTS - FTM)) / (2 * (Team_FGA - FGA))) * AST
PProd_ORB_Part = ORB * Team_ORB_Weight * Team_Play% * (Team_PTS / (Team_FGM + (1 - (1 - (Team_FTM / Team_FTA))^2) * 0.4 * Team_FTA))
After all of that, we can finally calculate the player's individual Offensive Rating:
ORtg = 100 * (PProd / TotPoss)
As a side note, we can also calculate what Oliver calls Floor Percentage, which answers the question, "What percentage of the time that a player wants to score does he actually score?":
Floor% = ScPoss / TotPoss
The difference between Offensive Rating and Floor Percentage, Oliver notes, is the average number of Points Produced per Scoring Possession. "Though [Shaquille O'Neal] may have a high floor percentage," Oliver writes, "his poor foul shooting means that he has a lot of one-point possessions, bringing his offensive rating down a bit. Good three-point shooters like Reggie Miller, who may not have the highest floor percentage, will have higher offensive ratings."
On a side note... to really see this work, BBRef calculates the ORTG and DRTGs in their boxscores, so when you see someone have weird +/- in normal box scores, head over to bbref's box scores to see how each individual player contributed to the overall score based on their time on the court. That player may have been on the court with other players who either tanked or helped their +/-. Is it exact, no, but it gives you a much better representation of what a player brought to the team in that particular time frame.
For a quick example(an unsual example for Towns), the Wolves vs Miami, Towns is +6 in the game but had 11 TOs but shows up in BBREF's ORTG as 68 for the game... he personally cost Minnesota 11 possessions, not Wiggins, not Tyus, not whoever... Towns. It lets you see that player's impact on the team during his time on the court.
https://www.basketball-reference.com/boxscores/201904050MIN.html