Rewatching "Emissary" for the first time a couple of years ago, I was struck by what an amazingly bad impression Sisko made on long-time TNG fans. He has all this anger and resentment towards Picard, and we know that Picard is still deeply traumatised by his assimilation and the massacre that followed, so WHY IS HE BEING SO MEAN?

It was a brave choice, to set the new hero up in opposition to an established and popular character like that, but it also encapsulates how DS9 had to fight an uphill battle from the get-go.