Complex sentence: An All-American offensive guard and tackle, Thornhill, who had the ironic nickname "Tiny" due to his imposing size, played in the first-ever National Football League season in 1920 for the Cleveland Tigers and Buffalo All-Americans.
Split into simpler sentences: An All-American offensive guard and tackle, Thornhill, who had the ironic nickname "Tiny" due to his imposing size. He also played in the first-ever National Football League season in 1920 for the Cleveland Tigers and Buffalo All-Americans.