Here is a link that might be useful: Mazus Reptens Death?

I'd try cultivating the soil in that area and add some peat or compost, get rid of the dead foliage and water well. Mazus prefers a moist soil - soil here looks a little on the dry side.

Mazus is my favorite low groundcover. I purchased some shabby ones this year that didn't look so great, but I kept watering and fertilized and they popped back. Great specimen.

This is the url to see the mess I have: Not Good.
Thnx and hope you can help further. Can't figure how the crawlers keep on crawling when the crown is dead. I've scratched away as much brown as possible and have been watering, I'll try the fertilizer suggestion; hmmmm maybe that was the problem to begin with (when I did, that is) Waddaya think for spring comeback?