I wanted Problem Boy removed from my class. I was told that it isn't right to give my baggage to another teacher and he stayed with me.
Ms. Cutie Pie had trouble with Problem Girl. Problem girl is now in another class. It was perfectly correct for her baggage to be passed on.
The playing field is so uneven it makes no sense to rate teachers on their students performance unless of course, you are looking for a way to get rid of someone.