The biggest shift in the evolution of the NFL has been the modern-day emphasis on passing instead of running. The second-biggest shift in the evolution of the NFL is even more tangible: players have gotten truly enormous.
In the early days, many players were large but still within the range of normal humans — around 200 pounds, and 6 feet tall. Today, the average player is now around 250 pounds, and 6’2" or so. The blob that forms at the top-right around the year 1995 or so is made up of today’s offensive linemen and defensive tackles, who are virtually all above 300 pounds and average about 6’4".
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