The facts differ with your statements. There is no reason to believe most high school 52+ 400m athletes are aerobic based athletes. Are you stating there are fewer high school 100/200 sprinters in the 52+ 400m range? Physiologists David Martin, PhD and Owen Anderson, PhD both state the 400m is a greater predictor of 800m success than 1500m performance. I believe there are about 130 sub-1:44 800m athletes in the history of T&F. Over 90% of said men have 400m PB in the (45.25 to 47.25) range. Having a sub-45 400m doesn't necessarily make one a slow 800m athlete. There are only 168 hours in a week. Athletes train very hard to get their 400m PB sub-45. I am not going to make a prediction of van Niekerk's 800m ability. I would agree with general thoughts of most posters. It would very difficult and unlikely for van Niekerk to race sub-44 400m and sub-1:44 800m in the same week. To state just because van Niekerk is the fastest 400m athlete that by default makes him a slow 800m athlete, is not necessarily true.