It looks like I have a few varieties of grass in my yard here in Los Angeles (including crabgrass). Mainly, I'm seeing these two. One is very thick and patchy and grows mostly around the edges and sprinklers. The other is what I think was intentionally planted here before I moved in this year. It's thinner and appears to be dominated by the thicker one and is also dying due to the sun. I don't think there was any of the thicker stuff when I moved here in March and the lawn was very healthy then.