@dchall_san_antonio, thank you very much for your detailed response. The company that is doing our weed spraying and fertilization came to discuss our lawn with us and indicated that we do, in fact, have Kentucky Blue Grass and the fescue so I suspect there may be some rye in there as well. He said the grass has some turf disease that will grow out. We've just had some exceptionally warm weather and little rain. By the way, we're in Northern Michigan, not far from Traverse City. Like you, he also recommended deeper, less frequent watering which I've been doing and I'm already seeing a big difference! He's going to aerate and overseed at the end of September, particularly on the sides of the house where there are quite a few bare areas. I expect the lawn will look better over time. Thank you, again, for educating me on taking care of a lawn. It's more work than the desert, but I'm grateful not to be in AZ right now!

"He's going to aerate..."

NAILED IT. Core aeration will do no harm, but it might get your expectations up. Be sure to do the screwdriver test before and after to see that the aeration gave no significant improvements. Let's see if I nail that, too.

@dchall_san_antonio, I'm going to schedule the overseeding. Should I ask him to skip the aeration and just have him overseed?

I missed your reply, sorry. Since you changed the watering, have you seen an improvement in the poor areas you photographed in the original post?

My low opinion of core aeration is not the common one. I did it once and there was no change to anything. When I sprayed shampoo I saw a remarkable change in the soil hardness. Now I refer to it as soil softness.

I did not mention shampoo earlier, so here's the 411. If you suspect you have hard soil, one application of shampoo at a rate of 3 ounces per 1,000 square feet will soften it for the foreseeable future. Here's the difference between core aeration and shampoo 'aeration.' When the coring machine rolls over the yard it pulls a few hundred plugs out of the soil. The distance between the open holes will be several inches. As the irrigation and rain comes the plugs will melt onto the surface, and the holes will fill with the surrounding soil as it melts into the open space. When you use shampoo, what happens is the surfactant in the shampoo allows water to be taken much deeper into the soil. The deeper water will cool and be cooled by the lower temps in the deep soil. It takes much longer for the deep water to evaporate which sets up the perfect living environment for the beneficial soil fungi. If you have ever seen what happens inside a bag of moldy bread, the same thing happens in the soil. These fungi send out long strands, called hyphae, through the soil. When the hyphae are moist they swell and push the soil particles apart. When they dry out they shrink which opens microscopic holes in soil. These holes allow air and, eventually, moisture to return to the soil when it rains or is irrigated. The holes become lined with a bacterial slime which hardens when it dries out. So these microscopic holes are real and long lasting as long as the soil is watered regularly (as described way above). There are literally bazillions of them, not just a few hundred or a few thousand. I have sprayed the soil at three houses as we have moved around, and the results are the same. When the soil is dry it is very firm. When the soil gets wet, it becomes very soft to walk over. One yard was so soft it was like walking on beach sand and a real ankle workout. The effect lasts for years and years. We are currently in a drought so bad that the soil in the garden where there is no lawn is cracking wide open, but when I watered the cracked area last week it returned to the almost-too-soft condition. Also there is a reason why NOT to use dish washing liquid. Dish soap has anti bacterial chemicals in it. Shampoo does not. The idea is to improve the soil biology, not to destroy it, so stick with shampoo. The clear shampoo you can get at Dollar Tree is fine and makes the yard smell like apples, or, whatever.

What do you consider "deep watering"? Would that be having the sprinkler on for an hour or more?

Esther, go back to the first reply to this topic. I explained watering there.

Dchall, about how many hours would I have to leave my sprinkler on until it "fills cat food cans"?

I cannot tell you. My oscillator sprinkler on full sweep takes 8 hours, but my neighbor has a high-flow, in-ground sprinkler system which fills the cans in 20 minutes. You will have different sprinklers, different water pressure, and different hose from my situation. Everyone has to test this themselves.