A question for someone who knows more about LiIon batteries than I do (ie virtually everyone

)...
Suppose my Gen3's battery dies after a couple of years. Will the replacement battery I got in my Gen3 "deluxe pack" be in any better condition than the one I've used in the machine, assuming it's just been sitting there in the box untouched for two years?
ie, do they degrade simply with time, or with charges (or both)?