If you are going to give him a role or a new position, apply those skill points before he has enough skill points to reach the next star. (phrased another way...make sure he never has enough skill points that if you applied them, he would be a five star player)

Once he has enough skill points in the bank that would make him a five star player, his training speed will slow down.

Your American like me, so you can easily power train him with green packs from watching videos.

And I would just train him, no games. He is rated lower than your current players. Let those guys win the league for you and let him be a reserve. Next season, a starter.

(or, see how much his condition goes down vs skill point gain...and decide which one grows him faster)