I just talk from experience as a lot of my clients are casino hosts, pit bosses, managers, and senior managers @ the casinos.
All experienced players place their players card down w/ the initial bet and someone will take the card and put down the time you sat down, time you got up, how long you played, what your average bet was, how many wins, how much you lost, etc.
But in Vegas-speak, "ratings" are just a series of #s that indicate your time, loss, win, etc.