How Fairly Can We Compare Generations?

How fairly can generations be compared in your opinion? Of course the basic principle that there is limited footage on the era of di stefano, puskas, pele, and even maradona is a pretty big contributor towards the doubt, along with other factors such as arguable advancements in technology such as match balls and other vital equipment. Other factors that should be considered is the idea of football in culture and how seriously it was taken by the players even 30 years ago, having an effect on the physical conditions of the players. Advancements in technology, fitness, and even formations and the idea of how football is played are all factors as little or big as they may be.

Can a footballer down to the very essence of the talent and player in it self really be compared, or can legends such as pele, george best, di stefano, beckenbauer, be put aside in an argument suggesting that the newer the generation, the better because of several complexes? Is it the same case as in tennis where a bjorn borg could not possibly be compared or realistically even have a chance of winning due to the ball, and racquet technology, change in the speed of the game, the proffesionality of it, and the fact that physical marvels like nadal have surfaced?

Some say it was harder to play with the type of footballs used in the past, some say that some type of players have become so obsolete that comparison would be irrelevant, or that culture has changed and so has the culture in which the sports life is lived, the footballer like ronaldo being a physical marvel compared to a rather comparably puny player like george best..

Can legacy be the only thing compared, and if so, how does the irrelevancy of the actual comparison NOT make the legacy irrelevant in many ways? If football has seriously changed its actual essence into a much higher level, how could legends be taken seriously in real terms against the new breed?

Is it a case of a mclaren from the late 90s compared to a veyron of the 2012 age?

How much is comparable in the history of football between the players themselves?

It might be irrelevant to try to put a player in another era in many ways, but we cant attempt to do so unless we spot the differences right?

How farer up in height has the bar been placed?

What can we really compare?

Example, how do you think distefano can even be looked at? Legends of him being able to play all over the field in the 50's sound like a joke now dont they?

How would a van basten or maradona fair now? How would a messi or ronaldo fair against men who were maybe not as close to being defined as a true proffesional as others in the past?

Another question..if not really easy to compare, how far can we go in time and still consider the type of player relevant in a comparison?