It can still be explained. Rank is irrelevant, it's how many marks that separate her from the other students that matters. If she was 5 marks away from 1st place, then she'd still have a relatively high mark, even though she was ranked 60th. If the bottom mark was reasonably high, and she was only a few raw marks away from rank 1, then 95 is a very possible mark to achieve. How ever many students who got 90+ in the exam doesn't matter - it's just the highest/lowest exam marks which matter and how she positioned herself relative to other students, which matter.
I can assure you that this isn't some "exception", and that it wasn't solely due to her performing well in the externals.