Mercy is refraining from ridiculing or abusing the young men who lost 91-0. Mercy is complimenting them for their effort. Mercy is treating them like athletes and competitors after such a loss. Mercy is applauding when they return to the line time after time against hopeless odds, and when they return to practice again the next day. Mercy might be sitting down with them and telling them about times you lost badly and how you felt and how you got up again. Mercy is pointing out to other kids the character it takes to keep trying under such circumstances, and challenging them to have character like that. Mercy is teaching kids how to deal with the adversity they will certainly face in their life.
It is not merciful to teach them they have a right not to lose badly.