A team's strength of schedule was calculated by win/loss record of opponents (66.6%) and cumulative win/loss record of team's opponents' opponents (33.3%).
Broad and sustainable change is only achieved when such activities are implemented in a long-term and cumulative way, mutually reinforced across various settings.
The integral of any smooth, positive, bump-shaped function will be sigmoidal, thus the cumulative distribution functions for many common probability distributions are sigmoidal.