For all of Heyward's issues he's still a plus defender. Zobrist is not, and his good last 3 weeks aside, I'd rather see him on the bench than Heyward, especially facing a pitcher that has the ability to shut us down. It seems like you're just glossing over/completely ignoring the fact that Zobrist is a much, much better hitter, especially vs. LHP. No, I understand Zobrist is a better hitter against LHP, but I value Heyward's defense more.