Complex sentence: In 1984, Vega began his career as a journeyman rider as one of the top riders in the nation, 7th overall in the U.S. for wins, and 29th on the list for earnings.
Split into simpler sentences: In 1984, Vega began his career as a journeyman rider and one of the top riders in the nation. He was 7th overall in the U.S. for wins, and 29th on the list for earnings.