All losses, behaviours are determined by calculation, except a commander's death and a loss of a flag which are random.
During a battle, when two infantry lines were facing each other, the volleys of shots killed few men, wounded hardly more and produced a lot of smoke. Battalions used to be routed by the loss of confidence : few men step back, and their neighbours followed them.
Most of soldiers « out of fight » were either wounded or running away. In the aftermath of a battle, some may get back to their army, especially if it has been victorious.
If you look at the 3D view, regiments usually move back after sustaining little losses : it is coherent with the percentage of sustainable losses.
In my opinion, that is reason why routers are more than dead or wounded.
Friendly,
Pariente.