Well, I would not be so affirmarive on this topic. A thing is (almost) certain: take the same player from 5 to 8 stars in the same season and his ratings are going to drop. I did it several times and the same thing happened every time. On the other hand, your team is becoming better. And that's much more important. That's why I just do not pay attention to my players' ratings. Stars rule. I prefer a 8-star player who gets a 6 than a 4 who gets 9. By miles. As I said previously, I only take ratings into account when I have to choose between players with the same amount of stars. That might be wrong but at least it seems to be working ok for me.
But in this specific case, I think it does not matter whom you are giving the stars to. As long as your team makes progress: maybe use your greens to get all your players to 7 instead.