Tried the same thing last winter when money got tight and I honestly could not tell the difference once everything went in the pot. Frozen thighs sat in my freezer for a month, thawed overnight, and they shredded just as nice as the fresh ones I used to pay extra for. The only thing I noticed was the frozen ones let off a bit more water, so I just drain the bag liquid off before they go in. Some folks buy fresh out of habit or they want to pick through and grab the best-looking pack, which I get. Your wallet will thank you either way, but your taste buds won't know the difference.