After being drafted in the fourteenth round of the 1958 NFL draft by the New York Giants, Roberts opted instead to sign with the Toronto Argonauts of the "Big Four" (soon to be renamed the Eastern Conference) of the Canadian Football League, whose head coach was fellow Californian Hamp Pool. Forming what the Canadian Press called "the best all-round backfield in the Big Four" along with Dick Shatto and fellow rookie Dave Mann, Roberts rushed for 595 yards and five touchdowns, including touchdown runs of 67 and 85 yards.
Roberts, drafted in the fourteenth round by the New York Giants in 1958, instead chose to sign with the Toronto Argonauts of the Canadian Football League. Alongside Dick Shatto and rookie Dave Mann, Roberts formed a standout backfield, achieving 595 yards and five touchdowns, including two long touchdown runs.