Damage Hack or/and body-locked aimbot
Check his battlereports. From Zero to Hero in a single day:
Zero: Almost every Battlereport that is not from today:
http://battlelog.battlefield.com/bf4/battlereport/show/1/1044297251466631552/1888908509/
http://battlelog.battlefield.com/bf4/battlereport/show/1/1044279624220400576/1888908509/
Hero: Every single Battlereport played today:
http://battlelog.battlefield.com/bf4/battlereport/show/1/1044639853110264704/1888908509/
http://battlelog.battlefield.com/bf4/battlereport/show/1/1044622368722027392/1888908509/
http://battlelog.battlefield.com/bf4/battlereport/show/1/1044652732622472064/1888908509/
Reason: Multihack