Well they are losing and the fact that the propaganda campaign run by the tribes warring SIN is underlining, highlighting and reiterating the (accurate) fact that SIN is losing is starting to hurt morale within.
I prefer to look at it this way. Yes, statistically SIN family is losing their wars against RMC, HIRE and Fear but you have know very well that Nakoro will never admit it.
He will always have some sort of excuse or reason as to how the only way SIN's enemies gained any ground was thru luck and treachery.
However, due to the propaganda forums, Nak's bullshit is handily exposed for what it is not only to neutral observes but also to members of the SIN who read the forums.
They are now less to quick to believe Nakoro's version of events, hence less faith in their leadership, lower morale, etc.
I don't really know this much is applicable to the average SIn member but it was the sentiment expressed by the two i speak to sometimes (and I'm sure we can all understand that they may not wish to be identified).