I have just browsed through some of the games from the ongoing world cadet championship for girls under 8, and I have to say I was very impressed with the overall level of their play. They seem to be booked up on openings, ( for example, sicilian defence all the way to middlegame), while their rating is quite low, around 1000-1400 most of the time. Also their middlegame is better than their rating suggests. What is the catch here?