Chinch bugs strike first at the hottest part of the lawn. Usually that is in a corner where the hot driveway meets the hot sidewalk. If you've been getting a lot of rain, it likely is not hot enough for chich bugs. Have you had some clear skies for a couple of weeks to heat up the soil? Otherwise my first thought was fungal disease (lots of rain).

Can you post a picture? The best pictures are taken in the shade or on a cloudy day. If you could get one close up at about 3 inches away showing both green and yellow or dead grass blades, that would be very helpful.