1. Most containers contain enough air to draw water out of the beans. Freezer-temperature air is dry. Freezer-burn is where water sublimated out of your food. Even a small air pocket can ruin coffee.

2. The partial-thaw then re-freeze cycle is devastating for coffee because it results in surface water on the beans.

Just keep your beans in a cool, dark place. e.g. a cupboard that doesn't get a lot of sun.