Low Performance Problem of Naci Unuvar

Hi guys, this is my first entry here and that's because I had enough with Naci. Currently I'm playing with Galatasaray and doing quite well with the league and champions league, my squad is pretty well. I'm playing 4-2-3-1 wide and Naci is playing on the left side as an inside forward. His teammates are really good including Tierney, Haaland, Arthur, Tonali, etc. I'm unable to upload his profile because it's an online game and I don't have the save game file but it's really good as well including 18 finishing, 17 dribbling, 18 vision, 18 agility, etc. And none of attributes of inside forward is below 12, however, he performs really bad. Usually he plays with 6.20-6.60. Even in the games I score more than 7-8 goals he only scores 1 or assists 1. Only trait I added to him is "places shots". I'm really sick of his performance. The worse thing is his performance compared to his attributes, normally a player with that attributes should perform really high. I'm thinking of consistency as the reason but I've never seen such a case before. It is not a temporary case, btw. He is performing low for 1 year almost. And I tried everything (warming him, changing training, changing role, changing tactic, rotating him, renewing contract, etc.) How can this happen? And do you have any suggests?
Ps: I'm playing fm since 2012 and probably I'm very experienced in fm.

Sounds to me like he just doesn't suit your team.

Without a screenshot and some detail about what tactics you use and player instructions then it's really impossible to help. Does his assistant report say anything about his consistency?

some players need time.
For example, Mephis Depay and Leon Bailey both needed time to adapt.

I can suggest to try him in a new position and see if that helps his performances.

It is hard to say what can be good every game for you but it sounds like maybe he just does not fit.

Has happened to me before that a player with great stats, who you hope the best for, just does not perform.

I wish you well and recommend to try the player in another attacking position.

For example Jadon Sancho was ok at AML (inside forward) then i put him as AMR and he was great. Its not his strongest position but wow he plays better there!