Rumbler, if I may. I think when it was built it was seeded with brown top millet and Bahia grass, both summer grasses. The brown top establishes quickly, but dies in the fall, and has to be replanted the next year. That's what you saw. The Bahia can take the first growing season to germinate and sprout. Bahia should be more obvious the second growing season and get thicker with each growing season.

Ryegrass is a cool season annual, planted in the fall. It is what you see that is green around town now.