Formula for Team Drtg?

[mopper8]

I'm curious as to whether anyone knows the formula for calculating Team Drtg?

From a thread on the PC board, I'm interested in doing the Bulls Drtg before MJ came out of retirement and after in the 95 season.

[rk755]

From what I know, a team's DRtg is [(points allowed)/(team possessions)]*100.

Points allowed is easy, the formula for a team's total possessions can be found on b-r.com -

Poss
Possessions (available since the 1973-74 season in the NBA); the formula for teams is 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)). This formula estimates possessions based on both the team's statistics and their opponent's statistics, then averages them to provide a more stable estimate. The formula for players is rather lengthy and can be found in Dean Oliver's book.

EDIT: Did some quick calculations. With Jordan, the Bulls played a total of 1570.599 possessions, conceding 1653 points, a DRtg of 105.2465. Without him, 6033.089 possessions, 6276 points, DRtg of 104.0263.

ORtg was 112.6958 with him, and 108.6508 without.