You almost assuredly have at least one, if not multiple of the following things acting on your lawn.
1. Shade/Tree suppression of turfgrass – all grasses need at least some sunlight and good airflow to be healthy. Trees rob grasses of water, nutrients & sunlight.
2. Grubs - eating the root system of your grass.
3. Winter Kill - root system too shallow or not enough turf canopy cover to protect from extreme freeze (this one mainly applies to Bermuda grass).
4. Soil Infertility – A pH imbalance or lacking key nutrients like Nitrogen, Phosphorus & Potassium or other micro nutrients. We can take a soil sample and do a soil test.
5. Soil Compaction – we have mostly clay soil here in our area and it gets hard as a brick & roots cannot penetrate, core aeration & top dressing with “Rich-Mix” top soil will introduce organic matter, loosening the soil allowing it to breath.