When certain skills change because of training, the listed "best position" might change, but that doesn't affect how a player will play or what position you can/should play him at. The suggested position is just a suggestion - you can continue to play someone at whatever position is best for your team. The suggested position uses some calculation to determine which position would generate the highest salary for that particular player (I think). Generally, an increase in jump shot will move someone from PG to SF.