How did the influx of germanic tribes into the empire and the areas around affect the empire?

When Germanic tribes invaded into the Balkans, Gaul, and Spain, the Roman empire had trouble recruiting enough soldiers to fight against the pressures from the tribes. 

During the mid-third century, the state was forced to hire Germans from outside the empire to resist the influx of tribes. The soldiers were willing to only work for pay since they did not understand Roman traditions nor did they have any loyalty to the empire.