There's no reason why they can't make a great game. First off football is CLOSE enough to rugby so it's not like they have no concept of what football is and the NFL was there for quite a while. Look at baseball. Japan, Cuba, DR and other countries are producing more baseball players than we are and that's supposed to be a red, white and blue blooded sport, more so than football. I don't know many developers who have actually fought Locust or dragons yet Gears of War and Final Fantasy games seem to have no problem selling.
I'm not seeing this "ultra-positive" that you're talking about. They seem to be cautiously optimistic. They said"While I came away from my demo amazed by what Backbreaker has to offer, I acknowledge that it'll take a lot more playtime to fully grasp how deep the gameplay is. It may look pretty, but does it offer the depth that football fans have come to expect?". I wouldn't exactly call that glowing.
Now whatever they piled on Madden was probably well deserved. EA talked all this garbage about studying NFL 2K5 and from what I've seen the only thing they took away from the game was close-up of the crowds in cutscenes. Funny thing is the demo seemed to play better than the actual game and that wasn't saying much.
You're half right. Madden 11 will come out. A bunch of people will post how great it is and how they are selling/trading in this and that to get it only a few weeks later to come to these forums crying about how disappointed they are in Madden 11 and want back in with Backbreaker