Is It Possible to Improve real players Rating in Career Mode?

Hi, I have a question. I'd like to play with a real player (Zizou Bergs). The thing is, I saw that it's impossible to level up the stars. Considering he has an overall rating of 83, and I'd still like to compete with the top players, does this mean it's impossible to improve him to, say, 88/89 after several seasons? And so, he and the other players will remain at their base overall rating, right?

Thanks!