nabla: It's not that hard to write an algorithm that can determine the winner regardless of the outcome of the outstanding matches most of the time isn't too hard:

For each player i, let W_i the number of wins he has, D_i the number of draws, and U_i the number of undecided games. There is a winner if there is an i such that W_i + D_i / 2 > W_j + D_j/2 + U_j, for all j != i. This is trivial to calculate. The only winners you might miss are the winners who finish with the same amount of points as other players, but win on SB.