Sanjay Ghemawat is as big as Jeff Dean. It is just that he is more of an introvert and takes a backseat to Jeff in the public discourse.
Here is a great article on their partnership: https://www.newyorker.com/magazine/2018/12/10/the-friendship...
Quote: But, for those who know them both, Sanjay is an equal talent. “Jeff is great at coming up with wild new ideas and prototyping things,” Wilson Hsieh, their longtime colleague, said. “Sanjay was the one who built things to last.”