Are land provinces with Shamblers unbalancing?

[Varangian]

In my past two games, I've taken provinces with access to Shamblers. The shamblers have good hit points and have very littl drain on resources (normally 1 resource per shambler). If you have cash, you can raise huge armies of shamblers each turn. I've been able to overwhelm the opposition once I get Shambler provinces. Are Shambler provinces unbalancced?

Varangian