modularity

Newman modularity Q of the partition, roughly [-0.5, 1]. Above about 0.3 means the groups genuinely correspond to how the modules depend on each other.

Near or below zero is not automatically a problem: a layered architecture is designed so that most edges cross a boundary - features depend on core, core depends on model - so a layer partition legitimately scores low. Read it as "are these groups also dependency clusters?", which is a different question from "are these groups correct?".