system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5 why are combat units “ineffective” after taking 15% losses?
gpt
A combat group is more than 50% support units and less than 50% actual gun/tank toting fighters. The losses are almost entirely actual gun/tank toting fighters. So a 15% loss is more like a 30% loss in fighting soldiers. 

Plus, there are usually more injured than killed and that takes way more support than healthy troops.