Original sentence: Wariner currently attends Baylor University (though he is not a Baylor athlete) and is coached by Clyde Hart, who was also the coach of Baylor alumnus and two-time Olympic 400m gold medal winner and nine time world champion Michael Johnson
Edited sentence: Wariner currently attends Baylor University (though he is not a Baylor athlete) and is coached by Clyde Hart, who was also the coach of Baylor alumnus and two-time Olympic 400m gold medal winner and the greatest 400m sprinter ever Michael Johnson