Neighbor's Dad was a grounds keeper at one of the golf courses in the area.
His advice was to bag the grass in Denver Metro Area.
Colorado is too dry for the grass to decompose quickly and efficiently, so it leads to thatch build-up.
He said Kentucky, where the blue grass comes from, has a lot more rain and the grass clippings left on the ground decompose fast and provide nutrients.
Good in Kentucky, Bad in Colorado.