"Does anyone know?"

As a percentage it may seem high, but with such a specific degree there will inevitably be people who find it's not for them. Three students from a single cohort doesn't seem that high - when I was teaching at uni the first years - across all the humanities disciplines - were dropping like flies.

When I was at a uni the first time round, at a theatre conservatoire in the States, we lost 15 out of a cohort of 30 in the first year. Lots of reasons - people decided it wasn't for them, too much pressure, too specialised, and sometimes just sheer bone idleness.