This story relates to the perfection of patience because the Japanese swimmer's mind was at peace through his patient learning from his opponents, and his consequent confidence. To learn from one's opponents, to be confident without arrogance or pride, is the bodhisattva spirit, and worthy of emulation.
Three Kinds of Patience
There are three ways to practice patience: patience with those who wish to harm us, patience with regard to the environment, and patience in enduring the dharmas.
Patience with Those Who Wish to Harm Us
If we do not respond harmfully when confronted by those who wish to harm us, we can avoid hurting others and ourselves. If we do not habitually respond negatively, it may seem that we always surrender, but we are actually developing the courage and skills to protect ourselves as well as others. In the long run it will be better for everyone. By analogy, if you refrain from chopping down a tree every time you need firewood, in the long run the forest is preserved for future use.