Much less demanding physically.. it's not any less demanding mentally, which is probably more what becoming a dad will affect anyways. Still they are two different people.. we'll just have to wait and see how it affects Roger. For the best I hope.
Ever noticed how exhausted new parents seem? It's very demanding physically. I'm sure Federer and Mirka will have a nanny on hand to help, but show me that person who has a newborn and manages to get enough sleep every night. Not to mention that physicality and mentality are arbitrary categories; the two are difficult to separate in real life. Should Mirka have any complications with her pregnancy or the baby any problem when it is born (knock on wood
), how could it not have both a mental and physical impact on Federer? I do think it's possible that fatherhood could have a negative effect on his tennis. But a joyous contribution to his life.
As for golf being as mentally demanding as tennis, I disagree. But please, I don't want to start an argument.