NFL height/weight data has been visualized before, but a new animation by WYNC's Noah Veltman may be the snappiest version yet. Over on his site you can watch the size of NFL players steadily expand through the early '70s, stagnate, and then spike again—mostly in terms of weight—in the late '80s.
It's clear from the two snapshots above that the NFL has become more positionally specialized over time; for a more in-depth breakdown of how football weights have changed by position, check out this offering from Craig Booth.