Complex sentence: Track and field was Hamilton's main sport, but he was also a second-string end on the 1921 Walter Camp All-American football team, and in 1923, he played on the Kansas City Athletic Club basketball team that won the National AAU Championship.
Split into simpler sentences: Track and field was Hamilton's main sport, but he was accompished in other sports too. He was a second-string end on the 1921 Walter Camp All-American football team, and in 1923, he played on the Kansas City Athletic Club basketball team that won the National AAU Championship.