Barry started running into the HOF on his first carry. There was no period of adjustment. Barry played in a single back set with no TE and no FB for most of his career behind a dilapidated O-Line and Lomas Brown. Despite a career facing those uphil struggles he is undoubtably the greatest runningback to ever play the game.
Reggie has a loooooooooooooooooooooooooooooooooooooooooooooooong (<---emphasis on the long) way to go before he's in the same class as Barry Sanders.
What they most share in common is their character and off-the-field class. Both reached out to their communities and did so without calling a press conference to do so. It just so happens that with Reggie the press follows him everywhere he goes.