In Hump Day Hangouts episode 200, one participant asked about the team's thoughts on the extent to which Google's Quality Ratings Guide actually affects rankings.
The exact question was:
How much do you feel Google's Quality Ratings Guide actually affect rankings? How much do you consider this when placing content or back optimize content to these guidelines?
BTW just bought this and i'll report back on its value. https://courses.mariehaynes.com/quality-raters-guidelines/