I think you can compare players from different periods, by comparing their effectiveness on the field compared with others of that generation.
If a player is a standout in one generation, it is most probable with all the different training diet, skill testing etc of this generation they would still be a standout. Sure the number of people playing the game has increased but cream always rises to the top.
I remember this argument in respect of Tendulkar and Bradman, and claims Tendulkar was a better all round batsman. Rubbish. Though fewer people played when Bradman played and the circumstances were different, when you compare other batsmen of his age with him, he was vastly superior. Tendulkar was very good, but so was Brian Lara, and now we have Steve Smith. Check their test averages and Tendulkar was on a par with Lara and both so far inferior to Smith (though this may change). None were exceptional standouts in this regard compared to other greats of that time. Bradman was.
So it is with players in Rugby League such as Eadie. His only challenger was Langlands, and Langlands had the advantage of playing in a St George side that was almost unbeatable for a decade. Same issue relates to Fulton and later Lyons. Lyons skill was almost unique with possibly only Andrew Johns comparable for the silky passing skill. Some would be standout no matter the generation