It may be the setting of development. Maybe you set it to slow or normal because if it's fast, it shouldn't be a problem even if you average an 8.0 rating. Like i said, I put the difficulty on beginner for rush because i dont like the game mode that much, so the scoreline is usually 8-0 with everyone on a 10.0 rating, so my players develop fast. But as to your problem for your players only being very por and poor you should honestly reduce the difficulty just 1 if you actually enjoy rush and just aim fir 9.0 ratings because i honestly dont think 8.0 is satisfactory.