I think this kinda theory applies to almost anything... for example the footballers of today (note that by football I mean soccer) are undoubtably better than the footballers of the past few decades.

I think this is mostly down to experience.. sport is continually evolving, with better technology and training techniques constantly being researched and updated. I think the demand for greater fitness and technique is higher than ever these days as money often plays a massive role in sporting events these todays, certainly considerably more than it has done a few decades ago when sporting events were pretty cheap to attend and the money generated was nothing compared to events these days... so I think athletes are pushed that little bit more to be at the top of their game for the money makers purpose.