This question is not a question of perfection, but one on knowing how to accept defeat.
Ignore perfection, it doesn't exist here.
Example:
Two somewhat equally matched teams play against each other; one team wins and one team loses. The losing team doesn't blame other people, or ill tactics, or carelessness or bad aim. They review the demo and aren't able to find specific errors or mistakes that caused their defeat.
What can they do now?
Simple.
Say: 'Good Game' and play again for the love of the game.
I find no reason to be bitter about it. I play to have fun, and I admit I have the most fun when I win a challenging game, but I'd rather have a good challenging loss then some 'definitive' formula to winning or perfect aim or having to hear the opposite team argue about who did what wrong.
I hope that's not just me.