Boxwoods have little tolerance for overly-wet soil (their roots need soil with a high oxygen content and good drainage), so it's possible some of the dieback is due to root stress or loss from soil staying too damp. It's hard to tell, since symptoms overlap between this an other factors.

We can't rule out an infection like Boxwood Blight -- a couple dark leaf lesions are concerning, but we can't see them very clearly -- but you can examine the foliage and stems for indications of disease mentioned in our boxwood diagnostic page as well as the page linked above.

What seems more likely in this case is heavy or cumulative damage from Boxwood Leafminer (also discussed in the diagnostic page), a very common insect pest which we routinely diagnose for Maryland gardeners. Many boxwood cultivars are susceptible, though a few are more resistant to damage. The leaves we see with an orange-yellow mottling and a blistered appearance likely hold leafminer larvae; we did see at least one leaf split open, presumably by a hungry bird looking for a snack, since some small songbirds do consume leafminer larvae. The adult gnats, which are orange, will probably make an appearance in several more weeks as the weather stays warmer. The insect only has one generation a year, and the simplest way to reduce a population if you want to avoid insecticides is to cut back the shrub to force new growth, removing the younger foliage that will house the next generation of leafminers. This is best done later in spring, once the adults finish laying eggs and die out, so the resulting regrowth is less likely to be injured by a late frost. Dispose of the clippings and do not compost them unless your compost pile gets hot enough to kill them. (Putting the debris into yard waste collection for municipal composting should be fine IF that is their only issue. Trash any clippings that are suspected of having Boxwood Blight.)

Some of the bare stems might have been afflicted with Volutella Blight, though usually we see the tan-brown, dried, dead foliage holding onto the stems for some time, compared to Boxwood Blight, which causes leaves to fall much faster (even before they turn brown). If there are any Volutella-killed leaves left, you can inspect them after a wet weather day or two to see if the classic pinkish-orange spores are present on the leaf underside. Volutella is a pathogen that attacks plants already under stress, such as from winter damage, over-pruning, or earlier drought. It does not kill roots, so plants may recover if drastically pruned back to force regrowth (if the living stems left are too scattered to look good). Given the slow pace of boxwood growth, a full recovery might take a few years.

Some degree of an orange-bronze blush to boxwood leaves can be normal for the winter. This trait is very variety-dependent, but also weather-dependent. However, when that color persists during warm conditions and into the growing season, it indicates a problem, and on shrubs with a patchwork of greener and orange branches, that uneven nature of the color change also suggests that the discolored branches are infected with something or otherwise are in decline.

If this degree of treatment or recovery waiting period is too long, the simpler approach may be to just replace the plants. If you plant boxwood again (not recommended if Boxwood Blight is present), you should look for one of the newer cultivars with resistance to that blight (and ideally also leafminer). Keep in mind that all they have is improved resistance; none are perfectly immune to the potential problems boxwood can contract. Otherwise, use a different species of evergreen; while everything has something it's vulnerable to, at least another species won't be afflicted by the same group of pests and diseases.

Miri