Same happened to me ...
I bought a 29Q 24yo ST and made him 30Q ST but he was very bad ...no goals and 1 assists per 4 matches ... so I decided to sell and asked for suggestion and sold him ... today I bought another striker with 28Q 25yo who scored 2 goals and 3 assists in his 1st match ...
in your case : if the ST is not performing up to the mark then show him the door ...buy another one ...but in the end you decide