Ok, so preseason is extremely vanilla and offenses hardly do anything to trick or misdirect opponents. We saw Speights and Hummel go against bad players and against bad, predictable offensive play calling. What we saw really has nothing to do with anything because everything they do in practices and the scrimmages between preseason games are going to be what tells the coaches if they are ready or not. So McVay isn't blowing smoke, they clearly do not like what Speights/Hummel are doing in practices yet.
Having said that, McVay won't shy away from playing them if he thinks they are the best option. But he is a bit of a stickler when it comes to practice and installing things during the bye. If we had beat the Bears I think we'd see changes over the bye week. Since we're a bit desperate at the moment I wouldn't be surprised to see some changes now but who knows.