Well the experience of a unit is based on the average experince of all the men in the unit. Thus in MTW when you retrain the unit and all the replacement had zero valour the amount the valour dropped was depednent on the number of men replaced.

I was undr the impression this had been altered back to work this way in M2TW from how it worked in RTW. But obviously not as it appears. Right up there with the dismounted/dismountable cavalry business!!