As I noted earlier no one thinks WAR is perfect. But everyone agrees defense is very important in valuing a player. And most would say that in terms of overall value, Heyward is superior to Freeman. Not theoretically, but based on actual performance during their major league careers, even accounting for Heyward's tendency to get injured more often so far.
Again, that really depends on just how much you value defense. I just don't think a definitive statement can be made that either Heyward has been more valueable up to this point and that he will be more valuable moving forward. To just quote WAR and try to make it an open and shut case I think it inappropriate.