The idea is let's line up the guy on your team by each position and compare them to the rest of the league. Specifically the top player at each position as well as the 15th best starter, the 30th best starter, etc.
Wait but 'best player' how? Based on what?
This is built on top of
ESPN's Real Plus Minus. An interesting stat that is meant to gauge the effectiveness of a player.
Real Plus Minus (RPM): Player's estimated on-court impact on team performance, measured in net point differential per 100 offensive and defensive possessions. RPM takes into account teammates, opponents and additional factors