I guess this last year Kersee has been raiding his medicine cabinet from the 1980's...
It's no coincidence that the only two women who have run 47 splits since the 80's are both coached by Kersee; it's no coincidence that it's the same coach who took crappy old VBH from 52 to 48 in ONE SEASON; it's no coincidence that his success has been primarily with female athletes, just like the GDR, because they react better to his medicine cabinet; it's no coincidence that he restricts his athletes competition programmes and withdraws them from races last minute; it's no coincidence that, under oath in court, Angela Bailey spoke about Kersee's doping his inner circle; it's no coincidence that Daryl Robinson accused him of doping athletes & Kersee didn't even sue (in the land of suing!).
That is where 47.9 and 50.6 came from. Prodigy or not, he is not stupid, he takes the best and turns them into super humans with his methods.