The bottom of the nomenclature section of the rules kind of explains this:
http://www.buzzerbeater.com/BBWeb/rules.aspx?nav=Nomenclature
* Outside Scoring, Defense: Both guards weighted heavily, small forward medium, power forward slightly.
* Inside Scoring, Defense: Center weighted heavily, power forward somewhat heavily, small forward medium.
* Rebounding: Center and power forward weighted heavily, small forward somewhat heavily, both guards medium.
* Offensive Flow (how well the offense produces assists, avoids turnovers): point guard weighted very heavily, shooting guard weighted medium, small forward weighted medium.
So for example to improve your outside scoring you'd want to improve the jump shot and range skills of your guards and small forward.