In 1973, O.J. Simpson gained 2,003 yards in 14 games with a rookie quarterback, a porous defense, and, in many instances, through severe weather conditions. He was faster and 30 pounds bigger than Barry Sanders, with superhuman diagonal acceleration. He was on pace to gain nearly 2,300 yards in a 16-game season. That record would have been football's counterpart to Joe DiMaggio's 56-game hitting streak -- untouchable.
Playing in a dome with an experienced QB and good defensive support, he probably would have gained 3,000.