I'm trying not to be patronizing, while at the same time pointing out that troops, or combat units as you put it, are always considered to be plural. The singular version would be 'soldier' or some variation of that. So... that would mean in regards to the topic of the thread, that it makes sense that as soldiers in the unit die, their offensive power drops.
You didn't read throughfully my post, did you?
Watch this. There are X's and O's fighting:
OOOOOOOO
OOOOOOOO
OOOOOOOO
XXXXXXXX
XXXXXXXX
XXXXXXXX
although there are 24 men per troop, only the front 8 are really fighting. So it's not 24 vs. 24, it's 8 vs. 8.
Now, X's take a beating:
OOOOOOOO
OOOOOOOO
OOOOOOOO
X X X
XXXXXXXX
XXXXXXXX
you'd espect it to be 8 vs. 3... but hey presto!, 2nd rank advances and closes the gaps of 1st rank (and so does 3rd to 2nd):
OOOOOOOO
OOOOOOOO
OOOOOOOO
XXXXXXXX
XXXXXXXX
XXX
so it's still 8 vs. 8.
That goes on until:
OOOOOOOO
OOOOOOOO
OOOOOOOO
XXXXXXXX
when X's have no more 2nd rank to fill the gaps. Then (and only then) X's start to shrink in width instead of depth, and it starts to be 8 vs. 7, 8 vs. 5 etc. But usually, at this point, X's morale fails and surivivors surrender, break or flee.
Now, consider that a troop deployed in line was 3 rows deep at minimum (usually a lot more), you can see by yourself that it makes no sense any dropping of offensive power until, at least, 2/3 of the troop "hit points" are depleted. "At least" means that 7/8 or 9/10 would be more accurate, so any minus becomes negligible, and the unit, being FoE battle system coarse as it is, could stay full strength untill its last breath.
That is, from a realism-oriented point of view.
P.S. unless all of this is just a misunderstanding due to my bad english.