My opinion - its largely up to how the Dungeon Master does things - that determines the enthusiasm of everyone. If the Dungeon Master is excited then the players will be too. If the Dungeon Master is just going through the motions or showing up whenever you can't expect the players to be enthusiastic.
Make sure to give them some Charm (Like their Post). Now that Charm shows everywhere if your new Player is being helpful or diligent make sure to "Like" their attempts so they aren't Posting with "None" under their Avatar.
Most Dungeon Masters do not see themselves as responsible for how enthusiastic their games are and put full responsibility on the player. I think its 70% Dungeon Master and 30% player for how good the game goes.