The average
The NFL average is so much lower than the other leagues because of the large number of players on each team and the high turnover rate, especially among fringe players. As a result, the average NFL player makes just $1.9 million and has a career of just 3.2 years.
Of course, most players will fall below these averages as there will always be elite players that pull the average up, such as Kevin Garnett, who has played 19 seasons and made more than $300 million in his career. However, this does give us a sense of just how much different the earning power is for athletes in different sports...
Data via Forbes.com, ESPN.com, NYTimes.com, QuantHockey.com
Data via Forbes.com, ESPN.com, NYTimes.com, QuantHockey.com