Babe Ruth changed the way his sport was played.
Bobby Orr preceeded Waybe Gretzky. Orr would have put up ridiculous numbers if he were a center. His numbers were insane for a defenseman.
Michael Jordan didn't win as much as Bill Russell or individually dominate as much as Wilt Chamberlain. There's nothing special about his numbers compared to other greats. Magic Johnson and Larry Bird had already brought NBA basketball to the forefront of public consciousness. One could argue Jordan didn't have a competent nemesis as competition.
While there is arguement Tiger Woods is the beneficiary of a cable/internet era, Muhammad Ali and Pele were beneficiaries of the beginning of the television era (Wide World of Sports).
Jim Brown was arguably the greatest running back ever. But he didn't change the game. The game he did change was lacrosse. There is a rule referred to as the Jim Brown rule. After Brown, players were no longer allowed to curl the ball against their chest and run over and through the defense.
Tiger Woods revived golf. The money increased incredibly. But there's already been the Jack Nicklaus - Arnold Palmer era. And for now, Nicklaus is the best ever. Palmer had the aura.
Babe Ruth is the king. He changed his sport more than any other.
Off the field the person who most impacted sports is Marvin Miller. He started professional free agency.