As god awful as he was in the field his bat is still pretty good for third base. He was the sixth best offensive third baseman in all of baseball last season, behind Cabrera, Longoria, Beltre, Wright, and Donaldson. Cabrera is moving to first and Donaldson had a career year.
Zimmerman has been fairly consistent with his bat at least so it's easy to argue that he's top five there. If there's some regression on the fielding it's not hard seeing him put up another 4+ WAR season.