There's a number of problems, the FC often attacks with range when he's in melee only stance (Even when surrounded). Then often when you are retreating a dying squad if a few units die they stop retreating and start fighting again allowing the enemy to slaughter them. Also if enough units inside a sqad die that you had in a control group sometimes you need to reset the control group. Units (Particularly vehicles and commanders) often get stuck in place when there is clearly room for them to move, I once had a dreadnaught stuck for 10 seconds right after being made after he was rallied to a place where there were no units or buildings even in flamethrower range, wtf?
Add more that I find.