Patterson was eligible for the professional basketball drafts after his second varsity season due to his earlier redshirt season. He passed up a chance to play for the Phoenix Suns, who selected him in the 1970 NBA Draft, and the Texas Chaparrals of the American Basketball Association, who chose him in the 1970 ABA Draft. Patterson re-entered the 1971 NBA Draft and was the first selection of the second round by the expansion Cleveland Cavaliers, and he signed with the Cavaliers.