If you go to your team page, click on the drop-down menu. And then look at "weekly stats". (Alternatively you can go to "Set your lineup!" and click on "weekly player statistics" underneath the roster information.) This page will show you who got minutes at which positions. Use this information to help you decide which training regimen to use. If you train 2-position training for PF/C then only minutes played at those positions will count for the 48 minutes you need to get the full training effects. So, in the situation you describe (assuming your SF only played at SF in the first 2 games), 2-position training for PF/C will only get your player 10 minutes of training.