smaller class size means less students...I guess school facilities (class rooms, teachers, etc.) have not been changed to accommodate the same no. of students of previous years.
1.) Less students in one class but same amount of people apply;
2.) More and more old boys or girls;
3.) More people are qualified to get points from religion;
4.) Second boys or girls can inherit from brother or sister;
5.) Most parents are now demanding and aimed for branded schools.
To add 1 to 5, it explains why less students for one class casues less chance now!