The balance is probably around 90% the car and 10% the driver. In the years of RB dominance, a subpar driver like Webber almost got the championship. OTOH Alonso lost a decade in Ferrari and McLaren while being, tied with Hamilton, the best driver in the grid.
The 10% of what the driver adds to the mix is what makes Hamilton champion instead of Bottas.
The 10% of what the driver adds to the mix is what makes Hamilton champion instead of Bottas.