The whole reason why it is difficult to break the pole vault world record is not because one guy had a radically different vaulting technique than other, but because everyone has maxed out on their poles. Elite pole vaulters continue to work out not only to maintain their current athletic shape, but they want to gain more speed and agility. This will eventually allow them to move up to a longer pole causing them to have a taller initial height as they let go of the pole at the top of their vault. More speed also allows for more energy to be transfer from the horizontal forces of running into the pole.
In order to move up to a larger pole, more energy is necessary in order to roll the bend of the pole to vertical. With a longer pole at a higher weight limit, the pole is stiffer giving more snap at the moment of straightening out. The snap will propel the vaulter higher after his final push off from the pole which at the top elite level is the main determiner of who wins. The current world record holder does not have to highest push off height meaning the measurement from top top of the pole to the apex of the vault. He holds the world record because his timing is perfectly correlated with the movement of the pole and his speed down the runway allows him to pop off the top of a stiffer pole.
Height also helps a vaulter use as larger pole as they leave the ground with the pole closer to vertical than a short vaulter. As I have stated in this blog before, the world record holder is significantly shorter than his main competitors. He levels the playing field with his speed which allows him to hold hire on longer poles than those with the same stature. When it comes to pole vaulting, At the elite level, one of the determiners of who comes out on top, pun intended, is who has enough speed and strength to use a bigger longer pole.