This looks like winterburn, a very common phenomenon that many evergreens are vulnerable to. Last year's drought across the state has not yet abated, and that's probably a contributing factor unless the hollies were monitored for watering needs and watered as needed. We've seen several examples of winter-burned shrubs and trees so far, and expect to receive more since it's been so dry and we had some notable cold snaps this winter. This damage happens because the water being lost from the leaves due to sun, dry air, and wind cannot be replaced due to dry soil or frozen soil moisture being unavailable to the roots. Cherrylaurel shrubs, Southern magnolia trees, camellias, and hollies are common victims.

Damaged leaves cannot heal, but the plant will shed them as it prepares to put out new growth later in spring. If they remain on the branch, and if new growth doesn't emerge from some branch tips, then the winter damage extended to the wood itself, and those branches need to be trimmed back to live wood. Hollies tend to regrow well, assuming they are otherwise healthy and the root system is in good shape, but how quickly they regain some fullness will depend on lots of other factors.

Complicating the diagnosis is the fact that this type of holly (it appears to be a "blue" holly, in the Ilex x meserveae group, which includes popular cultivars like 'Blue Princess') can be vulnerable to Rhizoctonia web blight, a fungal infection that can kill branch tips and brown leaves as a result. It's more prevalent in periods of wet weather, which can include irrigation when sprinklers wet the foliage. The recourse is still to prune out the damage, as fungicide treatment won't be able to cure an existing infection. Good air circulation helps to suppress the disease, and it looks like these plants have decent airflow because they appear to be out in the open (as opposed to planted too close to a solid fence or house wall). Avoid over-pruning them, where shearing creates a dense outer layer of foliage over time that restricts airflow, and the issue will probably be minor, if it is present at all. (We can't rule it out, but this time of year, the symptoms will be harder to distinguish from winterburn that killed stems in addition to leaves.)

In the meantime, just keep monitoring the shrubs for watering needs by feeling the soil about six inches deep and watering well once it becomes somewhat dry to the touch at that depth. Refreshing the mulch atop the soil to a depth of about 2-3 inches will help the soil resist losing moisture to evaporation. Since it looks pretty sparse now, you can re-mulch soon, even though the ground is still cool, or wait until later in spring as the soil warms, though that can risk some weed germination in the meantime since weed seeds have access to exposed soil.

Miri