I had almost the exact same impressions (I watched the stream). I think not having breakaway receivers limits the passing game. Every time there was a deep throw, there was zero separation - which, of course, could be a good sign for the defensive backfield.
While I am still not overly impressed with ZT, I do like the fact that he is reliable and consistent - you know what you are getting with him. We know we can win with a strong running game, throwing quick short passes and playing solid defense. It may not be pretty, but it is a path to a winning season.