The core of the ratings are based on statistical projections in 20 critical categories. Everything from personnel/coaching changes, player projections, past performance, continuity, training camp reports, and preseason indicators are factored in. This ensures a good balance of objectivity and subjectivity across the board. Each category crosses a notable threshold in statistical ratings and the size of each group will change as data accumulates.
With so many questions for each team, expect significant changes after 2-4 weeks of the season. I'll update the ratings on average once a month to reflect an acceptable amount of data, but I might do an extra update midway through September after we get an initial look at real performances/results.