I am probably the least qualified person to comment on this because I simply do not follow NFL media news very much at all. I 'happen' on NFL news... and even then I'm not that attentive, unless it's the Rams being discussed, of course... but that's my point:
I've seen the Ram's discussed a LOT this year. Of course it's still almost non-stop Pats/Steelers BUT.. other than those two I think I've heard more from the Rams than nearly any other team.... including the Vikes. The Eagles "maybe" I've heard more.
So the news is out there, I 'think'. But that doesn't say a thing about your theory that unless a known 'losing' team beats your own team it doesn't matter how much they are featured in the media they carry that 'losing' stigma, and confidently.... I think you may be right.