He's been outstanding in RF from all reports, making more than one game saving play. I have no reason to discount his +3 runs in RF given to him by Fangraphs. That said his true talent level is around 4 WAR (not 6) and no he won't live up to the contract.
But again who cares? Signing Harper wouldn't have prevented any other move Chicago would make, not then, not now, not in the future. The Sox are just cheap.