Kersee coached athletes own 4 world records out of the 22 standard events in track.
I'm not impressed. Three of those world records were set in the 1980s by drugged athletes.
And Sydney was able to set the 400h record because before her, the women's 400h was mainly run by women who weren't fast enough to make their country's 400 team. If the drugged women in the 1980's like Koch, etc. had taken the 400h seriously, Sydney might not have the 400h world record.