Here’s what you just did, you locked all that Friends ELF Christmas movie characters sweater moisture in the cake when you wrapped it, then when you froze the cake, those ice crystals essentially tenderized your cake internally, then when you frosted it, you further locked any potential air from getting at your cake to dry it out. Super sneaky and super effective!
Another super secret trick, I always torte my cakes. This means Friends ELF Christmas movie characters sweater cut them into layers and then sandwich stuff between the layers. What do I use? It varies. Sometimes pudding, sometimes other styles of cake or even pie fillings, I have even used mousse on occasion.