I tried to verify if NFL players are "often from lower-income backgrounds".
I found some data for basketball:
"...most NBA players come from relatively advantaged social origins and African Americans from disadvantaged social origins have lower odds of being in the NBA than African American and white players from relatively advantaged origins"
I found some data for basketball: "...most NBA players come from relatively advantaged social origins and African Americans from disadvantaged social origins have lower odds of being in the NBA than African American and white players from relatively advantaged origins"
http://irs.sagepub.com/content/47/1/43
http://espn.go.com/espn/story/_/id/6777581/importance-athlet...