One of Scott McCloud's more wacky inventions is the game Five Card Nancy which is based on the old comic strip Nancy. The basic premise of the game is that you can create lots of different (and fun) novel strips by combining random panels together. Scott recently posted an old collage he did that led to the game.
Of immediate note in his collage is that the sequence doesn't exactly make much sense, despite some cohesion between the panels. I'd say that it may have a narrative structure (i.e. visual grammar), but no meaning (semantics).
In some cases though, the juxtaposed panels do make sense, but the global meaning does not. In linguistics (borrowed from math), we'd call this a "first-order Markov chain", since only the units right next to each other have a connection. If a panel had a connection to two panels next to it, it'd become a "second-order chain", etc...
Markov chains were the primary way that people thought about language's grammar up until the 1950s, when Noam Chomsky then showed that grammar needed to account for connections farther than just countable individual word relationships (an approach I then applied to comics' sequences).
Essentially, McCloud's theory of panel relationships is a first-order Markov chain theory. It only looks at juxtaposed relationships. Interestingly, his Five Card Nancy game follows the same characteristic. Since players put down one panel at a time, it appears as though they are just making choices linearly. However, I'm guessing that the higher scoring combos are all ones that gel on a global scale, not just a local connection.
Also, the limitation of the panel transition viewpoint is really highlighted by McCloud's Nancy collage. How can panel transitions be correct if only local connections make sense but ones further down the sequence do not? Though we may draw and read comics one panel at time, it doesn't mean we don't build or project a bigger structure in our minds beyond the linear relations.