How do the hulking behemoths who play in the NFL today stack up against those who threw the pigskin around in 1923? Hoping to answer this question, developer and data journalist Noah Veltman mined the player profiles on NFL.com and put together a fantastic visualization showing the progression of NFL players' height and weight over time.
As you'd probably suspect, players in the NFL used to be a lot less gargantuan than they are today. In fact, back in 1923, a man who stood 5'-6", while still an outlier, was much more common in pro football. Compare that to today, where many of the shorter NFL players in the NFL are almost 6' tall.
But while players tend to be bigger on average than they were 90 or even 30 years ago, body types are less homogenous. For the first 70 years or so, NFL players were more closely grouped when it came to height and weight, but in the mid-1990s, that range became more distributed.
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.
Without seeing a breakdown of NFL player heights and weights by position over time, one can only speculate as to how a linebacker of 1923 would compare to one in 2014. Even so, it's probably pretty safe to assume that the players who serve as meat shields have gotten even meatier, while quarterbacks and wide receivers have become taller than their predecessors.
Check out the interactive visualization here.