I have not decided on my answer yet, however I will never forget when I found out Water Polo players were treading water the whole time... I was floored!! I was young and thought they were standing and playing ha-ha. (face palm)
@Kicker4Life @Giesbock
I always think of an athlete in terms of what they could achieve, beyond their current sport. Water polo players are ridiculous in their own right and are amazing athletes - big and strong. I don't think your average world class water polo player can train or be trained to cover Tyreek Hill. Speed isn't something you can coach/train. Take a look at Stephon Gilmore. Played football, baseball, and ran track. He was a quarterback in HS and set records rushing and throwing. He's now the #1 CB in the NFL. He has the physical ability to become a water polo player. He may not become the best water polo player, but I bet if he puts his mind to it, he can become a middle of the pack world class water polo player. He's 6'1", 190lbs.
With all of that said, Bo Jackson is likely the greatest athlete to ever set foot on a playing surface.