“Back in February, The Wall Street Journal pegged the average running back’s career at two years and five months.”

Please stop citing this flawed study; I’ve seen it in 3 or 4 different articles on here. It included hundreds of players who never played a down in the NFL. If you look at NFL running backs who suited up for at least 1 regular season game, the average career length is about 4.5–5 years. And it hasn’t dropped in recent years. SEE http://www.footballoutsiders.com/stat-analysis/2016/are-nfl-careers-really-getting-shorter.