Pope Paul VI is to the Catholic Church what LBJ was to American presidential politics. It was LBJ who pushed through the liberal social vision of Civil rights, war on poverty and the Great Society, all ideas Kennedy couldn't get through when he was alive even though he was the charismatic face that overshadowed LBJ. 

In the same way it was Pope Paul VI who actually implemented Vatican II and saw it to completion even though John XXIII either gets more recognition or credit.