Semi ot: advanced stat breakdown - implications

[Lukeem]

Looking specifically at drtg breakdown on basketball reference
" Defensive Rating
Just as Oliver's Offensive Rating represents points produced by the player per 100 possessions consumed, his Defensive Rating estimates how many points the player allowed per 100 possessions he individually faced while on the court.

The core of the Defensive Rating calculation is the concept of the individual Defensive Stop. Stops take into account the instances of a player ending an opposing possession that are tracked in the boxscore (blocks, steals, and defensive rebounds), in addition to an estimate for the number of forced turnovers and forced misses by the player which aren't captured by steals and blocks.

The formula for Stops is:

Stops = Stops1 + Stops2
where:

Stops1 = STL + BLK * FMwt * (1 - 1.07 * DOR%) + DRB * (1 - FMwt)
FMwt = (DFG% * (1 - DOR%)) / (DFG% * (1 - DOR%) + (1 - DFG%) * DOR%)
DOR% = Opponent_ORB / (Opponent_ORB + Team_DRB)
DFG% = Opponent_FGM / Opponent_FGA
Stops2 = (((Opponent_FGA - Opponent_FGM - Team_BLK) / Team_MP) * FMwt * (1 - 1.07 * DOR%) + ((Opponent_TOV - Team_STL) / Team_MP)) * MP + (PF / Team_PF) * 0.4 * Opponent_FTA * (1 - (Opponent_FTM / Opponent_FTA))^2
Also necessary is the calculation of Stop%, which is the rate at which a player forces a defensive stop as a percentage of individual possessions faced (essentially the inverse of Floor%, but for defenders):

Stop% = (Stops * Opponent_MP) / (Team_Possessions * MP)
With those numbers in hand, individual Defensive Rating can be computed:

DRtg = Team_Defensive_Rating + 0.2 * (100 * D_Pts_per_ScPoss * (1 - Stop%) - Team_Defensive_Rating)
where:

Team_Defensive_Rating = 100 * (Opponent_PTS / Team_Possessions)
D_Pts_per_ScPoss = Opponent_PTS / (Opponent_FGM + (1 - (1 - (Opponent_FTM / Opponent_FTA))^2) * Op "

Which is bound to turn into a bebe, jv discussion but I'd like someone with more experience with drtg to confirm or correct the following first

To my understanding within the breakdown blks are carried with equal value as stls or very nearly close to it



If that is true that is a major problem.

A couple things come into play here
1) def rebound % from a block or possession change is 57% http://www.82games.com/comm16.htm
2) total def reb % is generally high 70s%
3) for all intents and purposes every team shoots under 50% from the field
4) steals is a change in possession 100% of the time with a majority leading to one man advantages
And the highest predictor of a win https://fivethirtyeight.com/features/the-hidden-value-of-the-nba-steal/

Take a 100 possesion sample

100 possessions a team gets a shot off less than 50 percent will go down. But let's say 50 do and 50 don't. The 50that don't change possession 76% of the time which means 12 are retrained and subsequently 6 are made then another cycle through another 1 would be made. Putting it at around 57 makes total

Looking at those possessions dropping the retention rate makes a huge difference over 50 possessions blocked the offence retains around 21 possessions as opposed to only 12



Then with steals leading to easy offense as opposed to slightly more than an even chance at changing possesion the value of the degree of defensive stop is not valued at all in the stat however is obviously massive to success.



Something that is harder to measure but not noted above is the potential of intimidation

However with the current top 5 in drtg
Drummond 1
Gobert 2
Green 3
Whiteside 4
Howard 5

I can see imo way too much value given to the blocks of Drummond whiteside and Howard who have all been called into question for there actual defence