Ellis captained both the football and lacrosse teams as a senior for Ivy championship teams. As a defenseman in lacrosse, he was a two-time All-America selection, earning third-team honors in 1972 and honorable mention accolades in 1971 when Cornell won its first-ever NCAA lacrosse championship. Ellis was also a two-time All-Ivy selection in lacrosse, garnering first-team honors in 1972 and honorable mention in 1971. He was tri-captain of the 1972 lacrosse team. In football as a defensive end in 1971, Cornell tied with Dartmouth for the Ivy title. He was an All-Ivy honorable mention selection in 1970
