its totally based on software as software seems not optimising battery performance ....small tweaks run troughout which are main cause of battery drain......and battery generally doesnt gets detoriated easily so i think its sofware issue
"Thank you for Joining Samsung community. We would recommend taking some troubleshooting steps to further isolate what you may be experiencing. Find troubleshooting steps on provided link http://www.samsung.com/in/support/skp/faq/1101689. Please let the community know what steps you have taken and if you have noticed any changes or improvements. This will help the Community to provide you steps without repeating any steps you may have already taken. "
