See also: http://en.wikipedia.org/wiki/APBRmetrics
PER - player effeciency rating see http://en.wikipedia.org/wiki/Player_Efficiency_Rating#Calculation
TS% - true shooting percentage PTS / (2* (fga + 0.44 * FTA)
eFG% - effective field goal percentage (FGM + 0.5 * 3FGM) / FGA
ORtg - offensive rating PTS Scored * 100 / possessions
DRtg - defensive rating PTS Allowed * 100 / possessions
OWS - offensive win shares
DWS - defensive win shares
WS - win shares
WS / 48 - win shares per 48 minutes