Al Bundy writes:
Have you considered the possibility of disease or bugs?

Brown areas can be caused by this. For instance, grubs will chow on the
roots and create brown spots. You can usually grab the brown turf and
pull up a patch because they have destroyed the roots. Or if you go cut
down at the edge of the brown and pull up the edge you will actually see
the grubs. A prime indicator of grubs is skunks that dig in your yard.
People want to shoot the skunks not realizing they are doing them a
favor by digging a relatively small hole to eat their delicasy food,
grubs.

Disease is another story. Gotta ID it.

Bottom line whether it's bad mowing or someone spraying Triox on your
lawn at night, you gotta ID the root cause and not just throw stuff at
it like a jackpot.

Agree.

Not grubs cuz I applied Grub Ex in April. We also have had grubs
previously and this is nothing like it (no holes from squirrels, no
turf picking up).

Could be other disease but don't know how to identify.
Also, as mentioned in a reply to another poster, the whole lawn seems
to have been "shocked" into slow and anemic growth -- with some areas
growing very, very slowly (doesn't need mowing even after 3 weeks),
other areas thinned or admixed with brown strands of grass, and other
small scattered patches just all dead.

Any suggestions on how to ID disease or do you need to send a sample
to some "expert" somewhere?