If you have joined a game that has already started, open up the map with the "m" key. Each person on your side (Alliance or Horde) is represented on the map by a dot. You can mouse over the dots to see player names too. Where the players on your team are and what objectives your side controls can give you an idea of how the battle is going. You can review the Alterac Interactive Map for more details about the various important locations on the map. Also, you can open up the score screen on your minimap to see how long the game has been going. If the match has been going on for a significant length of time, it's possible there is some sort of stalemate in progress.