The concept of a "Rolling Hub" is basically this:
A "peaked" or "banked" hub has as many planes as possible pull into every available gate in fifteen minutes, drop off their passengers, pick up new ones, and each depart less than an hour later. This creates a traffic jam similar to the LA
freeway at 5pm Friday afternoon.
So the idea is to bring in the planes a little at a time, building up to capacity. In the first fifteen minutes, only about a third of the available gate space might be used. We'll call it a "section". Over the next fifteen minutes, another section, and the next fifteen minutes, fill up the gates. This prevents an over-capacity situation on the runways and long approach patterns.
Then, over the next fifteen minutes, the first section of aircraft departs. Sure, some of the people from the most recent inbounds can't make connections, but they aren't scheduled for them, and there will be a flight later in the day, anyway. Then the next section leaves. Perhaps another series of flights will arrive to take the place of the first section. Then, as more flights arrive, the last section departs, and the process is already starting over again.
That's about as simple as I can make the model. Obviously, there is more to it than that, but this should help with a basic understanding of the concept.
Another way to think of it might be of "continuous operation". "Rolling" gives the impression of aircraft always moving, never with all aircraft stopped at gates.
Those who fail to learn history are doomed to repeat it in summer school.