CNN sizes up swimmers and concludes size does matter but not so much weight. From CNN:
"... In the data, researchers noted, for example, that Duke Kahanamoku, who had world records for the 100-meter freestyle in 1912 and 1918, weighed 185 pounds and stood 6 feet, 2 inches. In 2008, Alain Bernard broke a record for the same race, weighing 190 pounds and standing about 6 feet, 5 inches.
But not everyone conforms to the pattern of increased height and weight -- at about 172 pounds, swimmer Eamon Sullivan weighed less than both Kahanamoku and Bernard, and also broke records for the same contest in 2008...."
[Link]
I like this kind of stuff. The last paragraph about a sprinter in the Roman Empire who weighed only 70% of what we weigh today was only a second slower in a 100 meter run.
In other words, size begins to hamper. Consider the size of a gymnast as compared to Alain Bernard? In a pound-for-pound ratio of strength, the gymnast may be stronger.
With that info in mind, also consider that a "heavyweight Greco-Roman wrestler" 2,000-years ago only weighed 140 pounds. That is hardly MMA or WWE material. To think that an average "Costco shopper" today would be considered a "bad-ass" both cracks me up and puts me in awe as to how far we have come.
Matt Greevers would indeed be a GOD! Oh well, instead he will just have to settle for being an Olympian!
Also note, the study did not take into account our speedsuits, caps, goggles, lane lines, and chlorine as compared to swimmers from 100-years ago.