Are you certain these are boxwood? There are also some hollies which look like this, such as inkberry hollies and helleri hollies. All of them are woody, but the inkberries grow like this shape with the 'bare, leggy' look at the bottom.
When you look at the arrangement of the leaves along the stem, if they are boxwood, the leaves would be opposite, or growing in pairs right across from each other on the stem, whereas for the holly the leaves would be alternately attached to the stem, every other one.
If they are indeed boxwood, take a look at our page IPM: Boxwood for ideas of what could be wrong here: https://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG52_IPM_Boxwood.pd...
We don't see any glaring signs of problems other than some winterburned brown and dropped leaves which would be pretty normal for the winter we just had.
We wonder about whether the needed cultural requirements are being met in your site.... for instance what kind of sun do they get there? Is the ground moist or wet at all?
We'd suggest getting your soil tested and here is the information to do that:
http://extension.umd.edu/hgic/soils/soil-testing, including a link to a chart listing of labs which can complete the analysis for you.
Finally, here is a Q and A from the National Arboretum which can provide more clues: http://www.usna.usda.gov/Gardens/faqs/boxwoodfaq2.html