Well, the Enweilian army /was/ considerably larger. Loosing a few battles and skirmishes tends to do bad things to your mobile CS.
Losses were completely unnecessary, though. I've seen sizable chunks of their army march off in random directions to get slaughtered by a massively superior force for no apparent reason, with other nobles continuously leaking to face death without explanation. Defeats did lower their strength, obviously, but most of these defeats were because of battles that never should have happened, unfortunately.
