Well, you can't use a big file from one game to another. It just doesn't work.I tried copying and pasting the big files from FIFA 11 into FIFA 16 folder and regenerated but it doesn't seem to recognize the .big files.
By big file, you mean the whole *.big file or its files? Also, the image formats are different in FIFA 11 and 16.
It is like cutting one animal's body parts and putting them in other animals and hoping it to work. There are procedures for it in FIFA Modding World and it's called "converting".