They're already in a shitty position, as central authority has pretty much collapsed in most of the fringes of the Empire, with local magnates being independent in all but name . Plus the looming threat of the Bulgarians, who were consistently beating Byzantine armies up till that point. And of the Seljuk Turks, who kept periodically devastating one of the only remaining prosperous areas of the Empire, the Meander River valley. And the rebellion of Sgouros in Greece, or the Komnenos brothers making a bid for the throne by occupying Trebizond with the help of their aunt in Georgia.
Given how long the crisis lasted, the Empire would normally have been able to call upon vast armies from the provinces. Here, there were none left able to be called.