
CCM's comment was is relation to units lost in the same battle, not multiple battles against the same opponent (thus why you tend (under certain circumstances) to lose 1-2 units an attack instead of 1-4).
@ Captian Rex, well at some point it gets worse. The number of units your opponent brings to battle also has an effect, so at high levels of allies you will tend to lose units even around 1/2 A/D (start looking at a 1/3rd, or get units with lower casualty rates)