From a quick check to your team iv seen that you have trainable players everywhere, but its not efficient to try to train all of them. Its better to focus on your guards for example, (PG/SG) 5 players, sell some others with upside and with that money buy some veterans to cover the positions that you dont train. It takes awhile to develop those youngsters but its well worth it. After 2-3 seasons you will have some great guards, selling 1 of them, buy a big man that you need. This is the basic idea of the game.