IIRC, the Avars at this time were in the process of societal change from more or less nomadic herders to the upper class of a multiethnic agricultural society, where a hodgepodge of tribes and remnants (Avar, Romanic, Hun, Slav, Gepid to name only the larger components) was boiled down to essentially 2 ethnicities, Avar for the leading class and Slav for the underclass, regardless of personal origins. The Maurician campaigns stripped away their nimbus of invincibility and the part of their warrior elite that is not needed to hold down their subject peoples is shrinking. OTL they spent themselves in the Balkan campaigns leading to the Siege of Constantinople 626, and were unable to keep hold of the peripheral regions of their Empire, not to mention the kind of invasions they mounted before. If they avoid that, their offensive potential is shrinking rapidly, but they'll keep more of their subject peoples in line.
