I want to talk about comparing era's in sports. A lot of people tend to give way too much credit to previous generations especially when it comes to thinking how well those players would do today. There are many variables you have to take into consideration when comparing these players. I'll try to hit the one's I think are the most important below.
1. Money. I've read that money isn't actually the best motivator but it's a good one. If you look up Champ Brown on youtube https://www.youtube.com/watch?v=vD182vPpunk you'll kind of get an idea of what the amount of money football players command can do to motivate people. The more popular the sport, the more money it makes, which attracts the best athletes. An example of how much money is there; Donald Sterling bought the L.A. Clippers in 1981 for 12 million dollars and just sold it for 2 billion dollars.
2. The pool of people to pick from. Anytime you have a larger pool of people to pick from you'll increase the odds of getting better people. A good example of this is in basketball. The Dream Team went a long ways in popularizing basketball around the globe. There's never been the amount of non American players in sports period that there are now. So in basketball, we now have a much larger pool of players to pick from than we did even in the 90's so the odds are greater that we have better players now than we did at any other time.
3. Genetics. It's common knowledge that athleticism continues to get better. I'm under the assumption that yes, we'll continue to improve but I do believe we're close to as fast as we're ever going to get. Think about this; humans will never be able to run a one minute mile. The fastest mile so far has been 3:43.13. That record will probably be broken in the future but at some point someone will run a mile that can't be beat.
4. Popularity. This one is pretty much the same as my first point about money. The more popular the sport, the better athletes it will attract. If Randy Moss type athletes were attracted to the long jump, we probably would've seen that record broken by now which was made in 1991.
So taking all of these things into account I will give you an example. Walter Payton is widely considered one of the greatest running backs to ever play the game. Now before I get too far I want to make clear that when we talk about the greatest of all-time, we're not talking about greatest relative to their competition because then they would not be the greatest of all-time. This gets easy if you just think of a sprinter. The greatest sprinter would be who runs the particular sprint the fastest. It's cut and dry because there's nothing to it other than how fast it was done. The same thing applies to any sport but they're harder to examine because of the other variables involved. Back to Payton. He was 5'10" and weighed 200 pounds. He averaged 1,286.61 yards a year for 13 years. Now I'm going to give you an extreme example of a player that would've been responsible for trying to tackle Payton, Lawrence Taylor. L.T. was 6'3" 237 pounds. Let's hypothetically say that L.T. was the average height and weight for his period. Now let's look at a one of the greatest linebackers of the 00's in Demarcus Ware. He was 6'4" 247 pounds. Now even that example, because LT was a freak of nature and Demarcus Ware, although he is too, is not head and shoulders above the average linebacker like LT was. Here's a chart to show the growth of players http://regressing.deadspin.com/chart-the-average-weight-of-nfl-rookies-by-position-a-1490494148. So Payton was playing against smaller, slower guys and averaged almost 1300 yards. How could anyone possibly expect him to run the same average against bigger, faster players? If Payton played today, it would only be logical to assume he'd not have the same success as he did then. Let's look at Adrian Peterson. He's 6'2" and weighs roughly 217 pounds. Bigger, stronger, and faster than Walter Payton. If Peterson played against smaller, weaker, slower people, wouldn't the logical assumption be that he'd perform better?
I can probably do this all day for all sports. Larry Bird is another example I like to give. I don't even think he'd make a roster today but I hear plenty of analysts claim him to be better than Lebron or that they'd take Bird in a hypothetical draft over Lebron. That's absurd. There's a reason basketball and football have combines. That people rise and fall in those combines because of height, weight and speed issues. Bird was 6'9' 225 pounds and one look at him actually playing https://www.youtube.com/watch?v=F_d6q3ll1qM will show you how unathletic he actually was. Lebron is 6'8" 250 and light years ahead of Bird athletically. I just don't see how Bird would even be able to get a shot off being guarded by Lebron.
Anyway, I love this debate and welcome anyone who has a comment.