NBA STATISTICS

Breakdown Sheet's uses a Relative Performance Index based prediction engine to simulate 10,000 possible outcomes for each game every day. Year-to-year performance varies greatly due to changes to coaching staff, roster, player health, player age and schedule so Breakdown Sheets uses only current season data in the model. Furthermore, NBA data becomes statistically significant after a minimum of 15 games. As a result, daily the first spreadsheet is typically published on Christmas Day.

THE FOUR FACTORS

The Foundation of Basketball on Paper.

eFG%

(FGM + (0.5 x 3PTM)) / FGA

Effective Field Goal Percentage is a more accurate representation of scoring efficiency because it incorporates the extra value of three-point baskets (+50% more than two-point baskets) into the equation.

When combined with a prediction on the number of field goal attempts in a game, it can be used to predict total points from field goals.

Dean Oliver postulates that shooting is the most important variable in the "Four Factors of Basketball Success" assigning it approximately 44% weight relative to the other three. Although he notes that this is just a league average and will vary from team to team.

[Editor's note: I agree that shooting is the most important factor, but it holds more than 44% weight in my models.]

TOR

TO / (FGA + 0.44 x FTA + TO)

Turnover Rate is a possession adjusted value for turnovers. This normalizes the value for teams running at a different pace and corrects of extra quantities racked up in overtime.

Offensive turnovers are empty possessions without the possibility of generating points by making field goals or free throws.

Turnovers forced while on defense are gained possessions for your offense. Getting additional opportunities to score multiplies the effect of the scoring efficiency metrics eFG% and FTR.

ORR

ORB / (ORB + Opp DRB)

Offensive Rebounding Rate is the percentage of total rebounding opportunities gathered by the offensive team. Like turnover rate, it is inherently adjusted for possessions with the value appearing in both the numerator and as a component of total rebounds in the denominator.

Offensive rebounds often lead to immediate scoring opportunities. Rebounds gathered close to the basket usually result in a quick shot from a high percentage zone or lead to a shooting foul. These both have a higher rate of scoring than typical offensive possessions.

Points scored after an offensive rebound are often referred to as second chance points.

[Editor's note: Offensive rebounding rates increase with distance from the basket since this negates the advantage of good defensive positioning or boxing-out. As a result, three point shot attempts have a hidden layer of value in that misses tend to land further from the basket than shorter range shots due to having more potential energy when impacting the rim.]

FTR

FT / FGA

Free Throw Rate is a remarkably deep statistic considering its simplicity. It considers both how often a team is able to get to the line and at what rate they make their free throws. And as with the other four factors, it scales with possessions since field goal attempts are highly correlated with possession totals.

As with effective field goal percentage, it can be combined with a prediction on the number of field goal attempts in a game to predict total points from free throws.

Oliver applies roughly 11% weight to FTR. That means when combined with eFG%, measures of scoring efficiency make up approximately 55% of each basketball game (compared to 45% for the metrics that measure extra possessions).

[Editor's note: Ken Pomeroy studied this ratio as it applies to college basketball statistics and concluded that "free throw rate is slightly more important in the college game".]

PACE

Game Speed & the Value of Extra Possessions

Game Speed

Tm FGA + 0.4 * Tm FTA - 1.07 * (Tm ORB / (Tm ORB + Opp DRB)) * (Tm FGA - Tm FG) + Tm TOV

Possessions per 48 minutes is not actually a count of the number of possessions in each regulation time NBA game. Instead it is an estimate of the number of possessions per game by using the above equation. It is made further accurate on a game-by-game basis through combining each team's possession estimate and taking the average.

This metric is commonly referred to as pace (a synonym of speed) since it essentially measures how fast a game is being played.

Pace is a product of coaching style. Some coaches prefer to emphasize the transition game by moving the ball quickly up court and having the effect of reducing the average time between shot attempts. Other coaches prefer to run a more methodical offense with set plays consequently resulting in more time between shot attempts.

Game speed drastically influences total score with one possession being about equal to one point scored. This effect is amplified at both ends of the scale. Slow paced games mean more time for the defense to set up which in turn leads to lower points per possession. The inverse is true for fast pace games since NBA defense has increasing effectiveness as the shot clock ticks down.

Extra Possessions

(oTO + ORB) - (TO + oORB)

Extra Possessions are calculated by finding the difference between turnovers forced plus offensive rebounds and offensive turnovers plus offensive rebounds conceded.

As discussed above, Oliver considers the two factors that measure possessions having a combined impact of 45% on an average NBA game.

NBA STATISTICS

Breakdown Sheet's uses a Relative Performance Index based prediction engine to simulate 10,000 possible outcomes for each game every day. Year-to-year performance varies greatly due to changes to coaching staff, roster, player health, player age and schedule so Breakdown Sheets uses only current season data in the model. Furthermore, NBA data becomes statistically significant after a minimum of 15 games. As a result, daily the first spreadsheet is typically published on Christmas Day.

THE FOUR FACTORS

The Foundation of Basketball on Paper.

eFG%

(FGM + (0.5 x 3PTM)) / FGA

Effective Field Goal Percentage is a more accurate representation of scoring efficiency because it incorporates the extra value of three-point baskets (+50% more than two-point baskets) into the equation.

When combined with a prediction on the number of field goal attempts in a game, it can be used to predict total points from field goals.

Dean Oliver postulates that shooting is the most important variable in the "Four Factors of Basketball Success" assigning it approximately 44% weight relative to the other three. Although he notes that this is just a league average and will vary from team to team.

[Editor's note: I agree that shooting is the most important factor, but it holds more than 44% weight in my models.]

TOR

TO / (FGA + 0.44 x FTA + TO)

Turnover Rate is a possession adjusted value for turnovers. This normalizes the value for teams running at a different pace and corrects of extra quantities racked up in overtime.

Offensive turnovers are empty possessions without the possibility of generating points by making field goals or free throws.

Turnovers forced while on defense are gained possessions for your offense. Getting additional opportunities to score multiplies the effect of the scoring efficiency metrics eFG% and FTR.

ORR

ORB / (ORB + Opp DRB)

Offensive Rebounding Rate is the percentage of total rebounding opportunities gathered by the offensive team. Like turnover rate, it is inherently adjusted for possessions with the value appearing in both the numerator and as a component of total rebounds in the denominator.

Offensive rebounds often lead to immediate scoring opportunities. Rebounds gathered close to the basket usually result in a quick shot from a high percentage zone or lead to a shooting foul. These both have a higher rate of scoring than typical offensive possessions.

Points scored after an offensive rebound are often referred to as second chance points.

[Editor's note: Offensive rebounding rates increase with distance from the basket since this negates the advantage of good defensive positioning or boxing-out. As a result, three point shot attempts have a hidden layer of value in that misses tend to land further from the basket than shorter range shots due to having more potential energy when impacting the rim.]

FTR

FT / FGA

Free Throw Rate is a remarkably deep statistic considering its simplicity. It considers both how often a team is able to get to the line and at what rate they make their free throws. And as with the other four factors, it scales with possessions since field goal attempts are highly correlated with possession totals.

As with effective field goal percentage, it can be combined with a prediction on the number of field goal attempts in a game to predict total points from free throws.

Oliver applies roughly 11% weight to FTR. That means when combined with eFG%, measures of scoring efficiency make up approximately 55% of each basketball game (compared to 45% for the metrics that measure extra possessions).

[Editor's note: Ken Pomeroy studied this ratio as it applies to college basketball statistics and concluded that "free throw rate is slightly more important in the college game".]

PACE

Game Speed & the Value of Extra Possessions

Game Speed

Tm FGA + 0.4 * Tm FTA - 1.07 * (Tm ORB / (Tm ORB + Opp DRB)) * (Tm FGA - Tm FG) + Tm TOV

Possessions per 48 minutes is not actually a count of the number of possessions in each regulation time NBA game. Instead it is an estimate of the number of possessions per game by using the above equation. It is made further accurate on a game-by-game basis through combining each team's possession estimate and taking the average.

This metric is commonly referred to as pace (a synonym of speed) since it essentially measures how fast a game is being played.

Pace is a product of coaching style. Some coaches prefer to emphasize the transition game by moving the ball quickly up court and having the effect of reducing the average time between shot attempts. Other coaches prefer to run a more methodical offense with set plays consequently resulting in more time between shot attempts.

Game speed drastically influences total score with one possession being about equal to one point scored. This effect is amplified at both ends of the scale. Slow paced games mean more time for the defense to set up which in turn leads to lower points per possession. The inverse is true for fast pace games since NBA defense has increasing effectiveness as the shot clock ticks down.

Extra Possessions

(oTO + ORB) - (TO + oORB)

Extra Possessions are calculated by finding the difference between turnovers forced plus offensive rebounds and offensive turnovers plus offensive rebounds conceded.

As discussed above, Oliver considers the two factors that measure possessions having a combined impact of 45% on an average NBA game.