Complex sentence: O'Donnell was given the nickname "Magic" for being able to drive a horse seemingly past its limitations, and was named Harness Tracks of America's Driver of the Year in 1984, a year when he set a yearly earnings record of over $9 million.
Split into simpler sentences: O'Donnell was given the nickname "Magic" for being able to drive a horse seemingly past its limitations. He was named Harness Tracks of America's Driver of the Year in 1984, a year when he set a yearly earnings record of over $9 million.