Answer: The matted grass is most likely thatch. Thatch build up is a natural process and consists of dead stolons, rhizomes and grass roots. It occurs whether you take excellent care of your lawn or you neglect it. Lawns can be dethatched about every 3-4 years. Rake to remove the debris and then reseed. You can do this in the fall or in the spring. In response to your question about fescue, the best way to eliminate it is hand pulling/digging. Weed killers won't be selective enough to attack the fescue without harming the other grasses in your lawn.
Best wishes with your lawn!
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