Lava, that doesn't look good. I dethatch once a year, each spring but that doesn't look like much thatch in my opinion. Have you fertilized at all? I know it's not great for the environment but starting last year I hired a company that does lawn care. He comes once a month and applies fertilizer. They have a program so each month the application varies. In the spring weed control mixed in, then grub control yada yada. My lawn looks great but I bet if I didn't have him it would look like crap.