When you crack the husk you release the fragrance and let the air into the innards of the malt. Kind of like if you cut a loaf of bread - what happens to the exposed sides... stale and not so good. Malt is not so timid as bread, obviously, but if left to the open air for long periods of time it will stale, especially if the air has high moisture content.
I have used grains that were cracked 6 months earlier, but kept in vacuum seals bags or airtight containers, with great results.
8-Paws Brewing Co.
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