They did longer stories, had better sourcing, showed more enterprise reporting, and did more stories about big ideas and issues. There is no magic bullet. The difference between quality that gets high ratings and quality that doesn't is many small decisions that add up.
Success is in the details.
For instance, master stations led all newscasts in having everyday people in their stories. People apparently like seeing people similar to themselves in the news. Another big difference is that master stations on average earned the highest possible score for covering a wide range of topics, while earnest stations averaged several points lower. Covering more of the community raised the quality score, and it also seemed to help ratings. Master stations treated more complex stories differently, too.