It's been going on for years Falc, and there's no reason to single out Nadal.
This article sums it up nicely.
Good article, but this guy walks among the clouds.
Sure, there is coaching in other sports, but that is about their culture. Tennis is a test of your individuality, a game played without help. In fact, when a player cramps up, in tennis he is not seen as hurt, but as unfit and unprepared physically.
Tennis isn't the purist game that many dress it up to be.
Tennis is "All That" but it's also a game of deception and gamesmanship.
1. in-match coaching
2. taking too much time between points, server and returner
3. changing your racquet when there's no changeover (Federer)
4. challenging calls you know are out just so you can buy yourself time to catch your wits or your breath (Federer)
5. bulls**t "injury" timeouts
6. bathroom breaks (Federer)
7. arguing with the chair (Federer)
8. lollygagging/tanking games or sets
I'm not picking on Roger here. I'm just noting that I've even seen Roger do 4 of the 8 on this list.