Its certainly just especulation when you have 42 years old / 15 years as a pro Demian Maia among best modern WWs, Woodley #1, and Lawler who has been around almost since twentieth century still ranked #10
That's a good point, tho I think the details is revealing:
Maia: is one of the only Uber elite Brazilian jiu jitsu guys that learned to wrestle and learned intelligent striking defense. Maia never relied on just athleticism, had great fight IQ and did not take tremendous wear and tear like Pele Landi or Wand.
Lawler: dropped from MW where he was too small, underwent a Anderson Silva like transformation (wink -wink) and got better as he got older, has been pretty fairly average under USADA but also had the sprawl and brawl style to give wrestlers that dominated welterweight problems. Lawyer also stopped hard sparring and accredited that to his resurgence, which is like Maia who does not take unnecessary damage in spars (i.e. "update the software without damage to hardware").
Woodley: super great genetics like other guys with great longevity (DC/Yoel), great wrestling base like DC and Yoel too, specifically dedicated lots of time to learning there craft of dat sic nasty hand game (again i.e. DC/Yoel), played the game very conservatively - even accused of being excessively boring, and sat out for long periods of time and complained to get his shots. Again we see fight IQ and smarter preparation/lack of wear and tear and updating the skillset plays an important role here/
There are just certain fighters that age well, both because of genetics, style and investing in to their careers, and others that do not. Just look at Mini Phil Baroni, aka Mike Perry: if you treat it like ghetto wars and not a career based athletic craft, your career and chin will resemble a ghetto war and you'll lose more often than winning. Being smart, cautious even, and improving with the game is so important. A guy like Pig-Pigg did not invest in his health like GSP and only cared to win a title and then stopped caring - he's akin to the guy that scores the chick but can not keep her. There is a reason a guy like him beat Askren in high school, was much more talented, but Askren out performed him in college and beyond because of his brain.