Just wondering what isn't under-rated when it comes to people's judgement of Nadal? we can't all be biased just because he isn't our 'idol' you know!
Since Nadal is a 14 times Slam winner, second only to Roger and tied with Pete, Open-era, I'd say that anyone who doubts his tennis IQ is underrating him. And I wish I had a dime on a dollar for every time a commentator says that Nadal is underrated at the net, or underrated for his soft hands. That's them saying it.
And then there are the Federer fans who feel that Roger was hard done by because Rafa beat him at Wimbledon in 2008. (He still had mono, he wasn't playing well, etc. And how can this possibly be the greatest tennis match of all time, if Federer lost it?) This underrates Rafa's peaking in 2008, and just getting the better of Roger.
Yes, I'm a Rafa fan, but it's not fandom that makes me see him as underrated. Perhaps I spend too much time arguing with biased people on tennis boards, but luck has nothing to do with his success. You can complain about his serve, but not his tennis acumen, IMO.