Looks like Zach will ruin the final season too
again, re-casting wasn't the problem so much as the mischaracterization. In season 1 he seemed old enough and smart enough to know what was going on. He seemed more stoic than emotional probably from having to be self reliant because of the circumstances with his parents.
Zach 2 is not just a bad actor, the writers pretty much completely changed the character into someone who is both bi-polar and very stupid. The best thing they could do now is kill him off quickly...and horrifically.