Specialized athletic ability. It's tough to find another Lionel Conacher
because you need to specialize in a sport now in order to get into it at a professional level. The all-around athletes get whittled out as you move up the ranks now. Remember the kid in high school that played on both sides of the ball in high school football? How'd he do as a cornerback in college? Remember the athletic quarterback in college that also played on the basketball team? How'd he do in the pros? Right.
There are some exceptions out there, but there's just too much competition for that to be a noteworthy reality any more.