Here is a zoomed in picture of it if that helps.

When you pull on the grass, does it come up easily? If so, check out grub worms.

Looks like your grass is wilting from drought stress. Water the area with your garden hose two or three consecutive mornings it will look better in no time.

If you have a sprinkler system and seem to have good coverage in the affected areas, I'd be inclined to agree with Marti that you have grubs or such.

At a glance it sure looks like those areas just aren't getting enough to drink though.

It may not hurt to post this over in the lawn care forum as well...

many times building debris is covered with a thin amount of soil. That debris will absorb heat and burn the roots of the grass. Try digging in those areas to see if that is the case.

Check if it's really that dry. Use a screwdriver to punch through in both area. If it gets enough water, easy to punch through. If it's too dry, it's harder to punch through.

If that bad area is easy to punch through, it's not water problem.

Still that grass is much better choice than bermuda that most of us get. :-( Biggest key for that zoysia grass is shade and drought tolerance. Bermuda has the worst shade tolerance.

Here is a link that might be useful: Palisades

Mine looks just like that when its really thirsty. Water restriction only allows me to use sprinklers once every 2 weeks, so occasionally I have to drag a hose out and give the spots some extra water. I find a soaker hose works well and usually within a few hours the grass will look noticeably better.