This may sound stupid, but I may have an idea that works. I once had a 5* striker who just could not score and kept getting low ratings. His lower quality strike partner was far better. After 9 goalless games, I was going to bench him, but his partner got injured, so he had to play. I put him alongside my 3rd choice striker, but he was still playing bad, until I swapped them round. He had always played as the left side striker. As soon as I put him in the right hand side of the pair, he just went mad. He got 10 goals in four games and received 3 man of the match awards.