Of course. Everyone knows that, not only is tennis harder and better and stronger today than at any time in the past, it is also hotter and more humid--thus more brutal.
It's global warming.
Ah, this explains the mystery of how heat and humidity when you have a higher temperature in the past is more brutal today. The global warning causes the sun to break through a tiny fraction of the Ozone layer to just focus on the tennis player today. Therefore the heat is more concentrated just at the baseline.