The article was an interesting read
Babblelot, and I liked the writers challenge of misheld perceptions. It doesn't surprise me that Federer makes efficient use of spin, but the statistics related to his use of it did surprise me.
As for Robredo, you raise the perennial point. There must be lots more players out there who can do a variety of things as well as or better than the top players / other champions, but their endeavours are unlikely to be scrutinised as much if at all, and they will not be brought into the equation in discussions such as the one raised in this article.
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I would like Johnny McEnroe's opinion on this theory behind Rafa's physique!!
Poor John played doubles and singles with great success for a significant period of time, and has no 'guns' to prove it -how sad!! 
Shouldn't that be "lady McEnroe!"

Seriously, though, JMac was an artist. Whilst we're at it, perhaps one of my all time favourites, Borg, would not be considered a "real" man either. But what use of the spin!!