The rules state that:
Each player that has played more than five minutes in a given match receives a rating, on a 1-10 scale. This rating is based on a combination of your player's stats and his overall contribution to the team effort. Note that this has nothing to do with the player's overall skill; if your worst player overall is the best on the court, he'll have the highest rating!
This is not correct as players can recieve ratings above 10.