Player ratings in Depth analyses

I finished 3rd in Premier league with Everton. But almost all my players have rating max 3 stars. I'm wondering do I need to make changes for my squad or does these ratings mean anything? Of course I can see av rating and I know which players actually played well and so on. But Now i'm on summer transfer period and wondering what should I do with my team.

For example my goalkeeper Livakovic has CP 154 (I have editor but I have not edit his CP) but rating is only 3 stars.

any ideas or help?

Presume you mean your stars rating on your squad screen which is judged by your assistant manager...?!

If yes then what is their rating for judging players ability & potential ability.

As to should you improve these players... well maybe, yes... But if they have key stats you like (Pace for example) then maybe not. It's just a star rating by an AI staff member for overall ability for that position. If you like what that player brings to the position/your squad & they have a good av. rating then you don't have to see it as a weakness.

Assistant Managers are almost useless on the game, they can be ignored 95% of the time. They are useful to me only as a pre game report on changes that might be needed as this is a good clue as to how the opposition are judging you & setting up against you.