Back in the day beat writers would often include a player's size in articles and part of the "facts" we suppose and if there was something going on with a player's weight in a particular year you could often read about it in the papers or in magazine articles and so on.
That does not happen as much today for whatever reason we've noticed. But in the 1970s, for example, it made for some interesting blurbs, anyway.
According to media reports in the 1973 season the Dolphins defensive end Bill Stanfill contracted some sort of illness or virus in camp or preseason and lost some weight. Usually listed at 255 or so pounds Stanfill was down to about 242 pounds for at least part of the season. Still, he played through it and whether he gained the weight back during the latter part of the season we don't know but it was a heck of a season. Stanfill was All-Pro and had a career-high 18½ sacks.
In 1977 Harvey Martin was listed by the Cowboys at 248 pounds, about 12 pounds lighter than in previous seasons and he, too, had a career-year that season with 20 sacks, was All-Pro and the Defensive Player of the Year.
In a book published early in 1978 written by Paul Zimmerman—Mile High: The Story of Lyle Alzado and the Amazing Denver Broncos Alzado revealed that after playing his career in the 265-270 range the Broncos coaches wanted him to report to 1977 camp at 240 pounds.
The logic was that the loss of weight would make Alzado quicker but still would be able to maintain his strength. Alzado pleaded with the coaches, according to the account, and a compromise was reached and Alzado played the 1977 season at 248 pounds. Again, it was a career-year, He was All-Pro and was the UPI AFC Defensive Player of the Year.
Surely there are stories of guys playing at an increased weight and having a career year and we're sure there are other stories of guys losing a few pounds to get that "extra step".
Did the lighter weights contribute to these players being vaulted to the next level of success? Was it a coincidence? That is unknown. Our guess is that there was some causation but how much is impossible to prove.
It seems in many stories we read from that era that players, seemingly defensive linemen, viewed their bodies as test tubes and were always tinkering to get the right formula—the right mix of weight and speed/quickness.
What does this mean? Not much. But it was sure fun to read stories like that. We wish there were more these days.