Just sell them and buy new ones.
I have had a striekr who player 15 games and scored 7 goals pretty lame.
But I stil have my 65 quality striker with one on one ability Sun Hoo Cho who has played 32 games in the league and has scored 31 goals.



Now THAT is a good striker. I have a 69 quality striker who has scored less goals than Sun Hoo Cho eve though he is better in quality.
Quality in this game doesn't really matter. Also try to balance the skills for example 65 defence 67 attack 66 physical % mental.