You are really on a downhill slope with hops. The colder and less air the better. Ideally you would flush with an inert gas and vacuum seal in something like mylar. Obviously this isn't a reality for most, but it should be noted that some hops really can change character after being opened (ie centennial) even if returned to a freezer. My routine is to order hops in bulk of 1/2-1lb amounts and then when I get them I vacuum seal them in individual packets of 1-2 oz amounts and put them all into an airtight plastic storage container that sits in my chest freezer. This is as cold and airtight as I can get, it minimizes frostbite, and it protects my other food in the freezer (if you ever have stored fresh hops in a poorly your freezer, such as a ziploc bag, you will have enjoyed everything taking on their character...mmm hoppy butter and bread).