In my view, a "mountain team" is a team who runs through the other mountain teams and then gets rolled by "flat land" teams. Or as you say, "lose by 40 on the road to a flat-land team." Greeneville might geographically be in the mountains, but Greeneville is elite. And you will have to go back a long way to find where they got beat by 40. Whether it is Knoxville, Nashville, Chattanooga or Memphis, teams know they are in for a 4-quarter game that will be down to the wire when they play Greeneville. And Greeneville has beat numerous teams from each of those "flat-land" cities in the last 10 years.
I think your characterization that "Greeneville struggles with teams out of flat land or Knoxville" is inaccurate. Here are some of the wins: Knox Catholic 2015, Knox Central 2015, Chattanooga Red Bank 2009, Chattanooga Brainerd 2009, Memphis Trezevant (state championship 60-12 ) 2010, Knox Fulton 2012 and 2013, Nashville Maplewood 2011.
Unless Greeneville wins the state championship every year, they have to lose to somebody- and that is going to be a team from Knoxville deep in the playoffs. If you think Greeneville is one of those "mountain teams" that doesn't have the athletes to play with the teams from the big cities, you are in for a big surprise tomorrow night. They have the athletes and the guys up front to play any brand of football that they need to.