# Gravity: Introduction to Bodies

Back in 2014, STATS Inc. introduced the notion of gravity, which was explained by Kevin Pelton as a series of two measures: gravity score and distraction score. In Pelton’s explanation, gravity score measures the relative distance a primary defender strays from their offensive counterpart and distraction score quantifies the amount of attention that same defender…

# Making Blocks Count

When we measure the defensive impact of a player, typically the first arguments we make are the number of blocks and steals that player has obtained. We celebrate players like Dikembe Mutombo and Maurice Cheeks for their prowess in obtaining blocks (2nd all time) and steals (5th all time), respectively. In the latter case, a…

# Usage and Efficiency

The usage of an NBA player consists of the number of chances a player takes out of the possible chances a team has when that player is on the court. A chance being the number of possessions that can result in a scoring possession. The higher the usage for a particular player, the more likely…

# Offensive and Defensive Ratings

The terms offensive rating and defensive rating refers to the amount of points scored by a team and by the team’s opponents, respectively, over 100 possessions. The normalization to 100 possessions allows for the ability to compare teams as pace of games can skew points per game comparisons. Both ratings are still considered box score…

# Defensive Ratings: Estimation vs. Counting

Defensive rating, a box score calculation, is an estimation procedure that attempts to identify the points per 100 possessions that an NBA player yields in a game. In this calculation, a player’s defensive rating is effectively eighty percent of their team’s defensive rating plus twenty percent of defensive points per scoring possessions when on the…

# Kinematics of Player Motion

After a couple special topics posts in Sketching and Voronoi Tessellation, we take a step back and look at the basic mechanics of player motion: position, velocity, and acceleration. Understanding computation and estimation of such quantities allow us to perform more important calculations such as trajectories, coverage, and crashing. The easiest way to capture these…

# Voronoi Tesselation and Rebounding Position: Defining Distance by Seconds

How likely is a player able to rebound a basketball? If you ask Second Spectrum, you will get a function that considers positioning, hustle, and conversion. The argument makes sense: First, a player needs to be in a position to have a chance at obtaining a rebound. Second, the player needs to be able to…

# The Art of Sketching: Trajectory Analysis

In a recent 2017 paper posted by Andrew Miller (Harvard University / Philadelphia 76ers) and Luke Bornn (Simon Fraser University / Sacramento Kings) titled “Possession Sketches: Mapping NBA Strategies,” the duo takes a well-known manifold learning technique called trajectory analysis and develops a methodology of classifying NBA actions through the use of functional mapping of…