Thorzain's weakest matchup is tvz and it shows. Even in the first game that he won I saw a lot of weakness. He set up a containment with tanks marines and thors, and kept denying Yugioh's expo attempts. The problem with that is that a good zerg would have muta harassed his lightly defended bases, Yugioh barely harassed his bases. Another problem is that the push is slow, allowing a good zerg to take over the map.
Thorzain needs to improve his tvz badly.