Today's athletes are bigger, stronger, and faster than they've ever been, and thanks to modern medicine they also have a better chance of rehabilitating from injuries that could have proved devastating in decades past. With the help of Dr. James Andrews, Grantland has explored how new techniques could have helped the careers of some of the best athletes around — from Johnny Unitas to Bill Walton. In the case of Joe DiMaggio and his infamous knee injury, for example, advancements like arthroscopic surgery could have helped him regain his speed. "With a complex injury like that," says Dr. Andrews, "a high-level athlete can get his career back — not guaranteed, of course — but you could get his speed and career back."