As of v1.3.0, you can use the "Average User Rating" field type to see an average rating from the Control Panel.
This is a read only field... it's for seeing the current average rating of an element. You may choose to use this field type if you have users rating elements on the front-end.
This field type really shines when viewing them as columns on the entries index.
If your stars use an optional key, you can specify that key in your field settings...