Keep in mind that BB sells a limited (they claim) number of advance reservation weeks that let you reserve a mooring the day before.

The do not, however, show these as reserved. It would be a whole lot more transparent if they did.
They get reset to the "available" icon along with the others.

That means that the "favorite" ball that you are hovering over at 6:59AM could already be reserved the day before and you never had a chance :-(