All right, I suppose that makes sense. But are those players now considered forwards when it comes to future training? Or are they still guards as they started out? I'm guessing forwards, but would like to verify that.
As with your lineups, you are free to train them in whatever you want to train them in. Best Position is merely a suggestion by the game engine. Those players of yours are whatever you want them to be. Guards or Forwards. You should only feel obligated to play them as forwards if you want to train them in inside skills, and as guards if you want to train them in guard skills. It's entirely up to you.