As the article state, Bend was 130 people at the end of production, but just 50 at the start. I doubt that they started hiring from day one. They probably grown the most in the last couple of years.Well Bend Studio was 130 people and Santa Monica Studios work on a lot of projects (not just God of War) so the employee numbers aren't directly comparable. Days Gone definitely feels the much larger game.
Santa Monica has its name on a lot of "indie" production because it seems to have the same role that XDev has in Europe. XDev has apparently 13 employees. I'm sure SSM dedicate some more people in this external production, but I dubt the numbers are really note worthy