The psychological aspect of both racing and training is incredibly integral to achieving success in swimming. Yoga can be a tool to develop many mental skills.
Now let me be clear, I am not talking about chanting, I am not talking about opening your chakras. What I am talking about is learning skills to reduce anxiety before races, monitor and adjust self-talk and visualize. All of which can be transferred to the pool.
Mindfulness. At one time this word was polarizing and drove people away from practices such as yoga because it was seen as wishy washy and synonymous with spirituality. Recently many of the most successful people in the world have credited a lot of their achievements to mindfulness practices.