Noah Veltman is a journalist who applies statistics to popular interests. Two months ago, we saw his charts illustrating the average costs of goods sold in fashion magazines. More recently, he created a cool interactive chart showing how NFL football players have gotten taller and heavier from 1920 to 2014.
Does this change reflect just how Americans have gotten bigger over the past century? Veltman says that further study would be necessary to find out:
You'd also need to look at the growth of athletes in other sports over time. If all athletes have gotten taller and heavier at similar rates, then it would reflect a general trend, but if, say, tennis players have stayed roughly the same size while football players have grown a great deal, that would indicate that football is still an aberration.
You'll notice that around 1990, the mass of data points began to separate into groups. Veltman speculates that this is due to specialization in football:
That likely reflects increased specialization of body type by position, with the heaviest group containing offensive linemen and defensive tackles, the smallest group containing defensive backs, kickers, and some running backs, and the middle group containing other position groups. Nowadays if you're 6' 3" and 280 pounds, you're too big for most skill positions and too small to play line.
-via Marginal Revolution