But as I was referencing in my first reply, there are no teams in Diplomacy and various levels of betrayal, frustration, and disappointment are explicitly built into the interactions among players.
A more appropriate (in my opinion) sports analogy would be Team A's frustration at Team B when Team B's poor performance in another game allowed Team C to hold better standing in a multi-team tournament, thus indirectly influencing Team A's prospects.
Even this is not quite right though because as I said above, I believe that playing for spite, revenge, and any number of other decidely social and personally determined goals, has its place in Diplomacy. These sorts of personal aims are generally unwelcome in team sports though.
One final point, since Draugnar mentioned a broader meta-game goal (not the anti-Maniac bit, but his intention to focus his energies on another league game). It is entirely common in some sports for teams to give less than their 'all' at the end of a game with a foregone conlusion, as part of a broader strategic plan to protect/rest their players for future games.
I think this is consistent with the habit of Dip players aiming for a particular record, sometimes accepting draws where they could otherwise win, or avoiding certain confrontations in some games in the hope that their behaviors will benefit them elsewhere. All of this is a form of (generally?) accepted meta gaming, which is especially common in the league tournaments I believe..