The block diagram is a very generic view to display any kind of graph data. The view follows your current context and depending on how you have managed the view modifiers options and perspectives, the components it is connected to.
This view is great to use when you are looking to create process diagrams, deployment diagrams, organization charts, or any view where you expect more structure in the flow. This view does not specifically take sequence into account.
Use groups (group by parent, workspace or reference) to clarify what you are looking at
Remember direction matters! (IT often thinks "bottom up" while the business users think "left right" or "top down".)
The configuration options to manage the degrees of relationships and reference filtering are in the first drop down:
Read about Graph Traversal to get more details about using the degrees of relationships and advanced settings.
Another configuration option is the drop-down to configure the layout direction:
And there is a toggle to exclude unconnected components:
Also Grouping is a very powerful feature to tailor a view.
To dig more into Block Diagram, check out these related articles: