Jonah Hill revolutionized baseball by using data models to predict success in Moneyball.
Wilt Chamberlain revolutionized basketball because they had to change several rules because of him. Shaq caused one rule change too.
But my vote goes to Dick Fosbury for creating the Fosbury flop. Before Dick came, everyone did the high jump forward. He was the first to discover that he could get much higher by going over backwards.
And the dude was serious about winning too. In high school, not every school could afford the thick foam landing mats. Some schools had wood chips or sawdust landing areas. It wasn't that big of a deal because the jumpers mostly landed on their feet.
Well old Dick knew it was going to hurt but he wanted to win so he did his backwards flop anyway and landed on his head/neck and got a fairly serious injury.
Still recovered and went on to win Olympic gold years later. And every single high jumper uses his method today.