Rafa has a draw that is as tough as hell. It's not that he can't win those matches... it's the cumulative effect it's going to take on him prior to a probable semi final clash with Novak Djokovic. Fog always gives Nadal a match (however unfit - he played him tough in the second set in Barca), Thiem is a future Roland Garros champion, Tsonga will make him work (although Rafa should prevail), and then he faces Novak. It's Novak's best opportunity to win Roland Garros.
That is a great post general.
The key for Rafa would be get through some matches rather efficiently and also get exactly the tests he needs to prepare for Djokovic.
Rafa also may end up facing the Italian clay monster that beat him 3 times last year as you have indicated.
Fog can be tough at times. He can take ball so early off both wings.