NEWYou can now listen to Fox News articles! While many of the Baltimore Ravens players have certainly excelled on the football gridiron, some of the NFL athletes apparently struggle in the swimming pool. After defensive back Marlon Humphrey and some of his Ravens teammates admitted they did not know how to swim, the team turned to a local expert for guidance. Michael Phelps, the most decorated Olympian of all time, certainly knows a thing or two about swimming techniques.