An evergreen is doing its job in February, and February is the whole argument for planting one. Five months of the year everything else is bare, and what holds foliage is holding the shape of the property.
February is also when it is under the most stress, and the cause is not cold. An evergreen keeps its leaves, so it keeps losing water through them all winter — and when the ground is frozen the roots cannot replace what is lost. Add a dry wind and the intense winter sun we get at this elevation and the plant dries out from the exposed side inward. The foliage goes brown and brittle. That is winter burn, it has nothing to do with hardiness ratings, and it is why the same plant thrives on one side of a house and fails on the other.
It decides what works here. Needled and scaled plants — pines, spruce, junipers — have less surface area losing water and a waxy coating holding it in, and most of them evolved somewhere just as dry. Broadleaf evergreens have more leaf exposed and show it. They can be grown here, on a north or east exposure, out of the wind, and they are a poor bet anywhere else.
Two things decide the outcome more than the plant choice does: where it goes, and whether it went into winter watered. A deep soak before the ground freezes is the most useful thing anyone can do for an evergreen in this valley, and almost nobody does it.