As aussie dude pointed out, training will be given to the players who played minutes in the last week on the position you are giving training to. So if you decide to give training to PG's and you let the player who normally plays center in your team play on the PG position for a change; he will receive the selected training.
So the listed position as seen on your roster of players is not relevant. To read more about training;
http://www.buzzerbeater.com/community/rules.aspx?nav=Trai...