if your guy is 22 then his potential is irrelevant because he will never reach it
i am assuming that you are a new team and my advice for new teams is to always train two positions
this will give you hopefully 5 good players by the end of the season if you keep the 2 you like the most and sell 3 you can buy a decent older player for each position you arent training
then next season add 3 more trainees to the 2 you kept and repeat