Student drop-out rates in themselves are nothing new.  In my university years (about 60 years ago) the success rate (first-year admissions to actual graduate numbers) in Engineering courses at Wits was below 40%.  
It seemed as if the university authorities at that time had found that matric passes were a poor predictor of graduation success, so they admitted almost everyone with a basic qualification who applied to first year, and applied a sink-or-swim approach during the four years leading to graduation.