There are no outside influences on a game of chess so the winner is ALWAYS the
player that played the best during the game in question. The repective sums of
differences for 'perfect' play will always be in the favor of the player that
won the game. If the losing player outplays the winning player and then
blunders into a mate in one, the negative value of blundering into the mate in
one must outweigh all of the errors that were made earlier by the winner.