We had the same situation as @saif235: every year multiple students getting into all but one of the tippy top schools. Nobody had any explanation- including parents who had been in the school long enough to have picked up scuttlebut.
Then one year a former student transferred in from another college, the next year a student whose sister had gone to a different secondary school and was a student at that college got in, and the next year an ‘unhooked’ student got in, and now the numbers look normal. But we never knew if it was that the regional Rep had something personal against the school, or former students had let the school down, or what.
If your child is really set on this college as their first choice, s/he could consider asking the question straight up in an interview: ‘is there any reason that you might think that a student from my school would not be a good fit with this college?’