Most companies are better at exhorting you to be a great manager, rather than telling you how to be a great manager,? Safferstone says. Project oxygen started with some basic assumptions. People typically leave a company for one of three reasons, or a combination of them. The first is that they don?t feel a connection to the mission of the company, or sense that their work matters. The second is that they don?t really like or respect their co-workers. The third is they have a terrible boss – and this was the biggest variable. Google, where performance reviews are done quarterly, rather than annually, saw huge swings in the ratings that employees gave to their bosses. Managers also had a much greater impact on employees? performance and how they felt about their job than any other factor, Google found. ?The starting point was that our best managers have teams that perform better, are retained better, are happier – they do everything better,? Bock says. ?So the biggest controllable factor that we could see was the quality of the manager, and how they sort of made things happen.