I think you have to consider guys like J. McEnroe and Jimmy Connors who came in and win the NCAA Freshman year and do so in dominating fashion. Not saying they were the best ever but deserve to be in the conversation.
Look at some of the players in the draw.
McEnroe - 24-0 single and team champion
Jimmy Connors - UCLA First freshman ever to win the NCAA D1 singles title.
Scroll down to 1971 men's tennis team.