English Boxwood failing
I have a row of mature English Boxwood about 50" high and 60" spread, probably planted when the house was built in 1937. It is on a bank on the northeast side of the house and has suffered die-back each year, but now is stressed and failing. The plants were sheltered by a mature (80') chestnut oak which died and was taken out two years ago, converting their site from high shade to full sun. The soil has been undisturbed and is likely compacted - my parents advised that resetting mature English Box is not advised - and I have not tried to manipulate the soil.
The boxwoods in the photos look like they have been subject to a type of stress. The roots may have been compromised due to drought. The roots are shallow and appreciate an application of an organic mulch no more than an inch or so. Keep away from base of stem. If you cannot water during dry periods, you may want to lay soaker hoses around the base of the plants.
The fact that the tree was removed may not be a bad thing. The plants look like they have been stretching toward the light. Prune off the tops of the shrubs (pom poms), lightly thin, and let them start to fill in. The best time to thin boxwoods is December through February. See our publication on boxwood for more information http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG52_IPM_Boxwood.pdf