I am not sure if there really is a good way on making records comparable. There is always the per game numbers. ie. 2000 yards in a 14 game season is 143 yards a game, in an 18 game season that is 111.1 But that doesn't really work for so many stats as the game changes so much. Baseball for example doesn't really change. The rules stay the same. Last years NL and AL batting leaders hit .336 and .359. In 1890, they hit .336 and .363. No real change in 120 years. The Giants played 157 games in 1898, they play 165 now.
The NFL is different. pre-1978 only Namath passed for 4000 yards in a season. Post-1978, Jeff George in 1997 is the only QB to lead the league in passing (in a non-strike year) with under 4000 yards. And rule changes/scheme changes (west coast offense) have had passing numbers shoot up. Young, Montana, and Aikman are the only QB's in the top 30 in comp% that retired more than two years ago. Young and Montana are the only ones in the top 16 of QB ratings. Nothing against Carson Palmer, but him having a better QB rating than Staubach or Marino doesn't mean he is a better QB.
Or look at Jim Brown. Greatest NFL player ever IMO. His 1527 yard 17 TD season is impressive, but even more-so when you take a look at his peers. The next closest back had 791 yards. He had a pro-bowl teammate with 651 yards and 2 TD's.
That is I think where you can find some measure of greatness.. Comparison to peers. Brown gained 1.93 yards for every yard gained by his closest competitor. That's like a 2700 yard season for Arian Foster this year. (Plus doubling the nearest guy in TD's). And Brown was doing things close to this EVERY SINGLE YEAR. I have often said that Jim Taylor would be on everyone's list as a top 5 back of all time (and arguably the best ever) if Jim Brown had stuck to lacrosse.
That I think is where you see Marino's greatness. The old record for TD's was 36. He broke that twice in 3 years. Not by 1 like Peyton, or Brady. But a full 1/3 more TD's. Put those increases in today's numbers.
50 is the current record... Now a QB would need to get:
66 TD's in year 2, then 42 the next year, then 61 the following year to stomp the records as hard as Marino stomped them. I was a kid those years, but those were just insane years for Marino to those that remember them. He was the only QB ever that I have seen to be what I would consider a lock for the Hall of Fame before his fifth year.
1 QB in the league threw over 28 TD's when Marino threw for 48. 4 did each of the years when Manning and Brady threw one more to set the records. When Marino threw 44, the next closest had 25! And he threw for 400 and 600 yards more than his closest competitors those two seasons as well. Just amazing. By his 4th season he had thrown for 30 TD's 3 times. That was a record (as was his three 4100 yard passing seasons), and you could count on one hand the number of QB's who had done that multiple times in their careers (and on one finger the multiple time 4100 yard passers).
Yes those numbers were in a huge part due to the rule changes, and 16 games of 1978. But the fact that they have stood so long and were so dominant over his peers of his time, makes them most impressive to me.
So I think ranking vs. peers is really the only good way. Saying team x's defense allowed 100% fewer points than the league average for example. And not even this is a perfect situation. I don't know if going up against the D's of the 30's was as hard for Hutson as Rice matching up across from Deion. The game is just so different.