Last year, Nadal won only one of the four tournaments on clay before cruising to the Roland Garros title, falling to Ferrer in Monte Carlo, Almagro in Barcelona and Djokovic in Rome. He may have been on his way to losing to Nishikori in Madrid before Nishikori had a back injury. 

But this year Nadal's slump appears more serious. Djokovic beat hiim 6-3, 6-3 in Monte Carlo even when Rafa hit the ball pretty well. Fognini beat him in straights today despite being down a break three times in the second set, then blowing three match points in the tiebreak. Fognini played very well, but Rafa's errors were shocking, including a Federer-like mishiit on a forehand and a sitter forehand he hit well long to end the match. 

From the start of 2005 until today, only two players had beaten Nadal more than once on clay --Djokovic, who did it five times, and Federer, who did it twice. Now Fognini has beaten him twice in a row on clay this year. 

At his peak, Nadal is still better than Djokovic in a best-of-five set match at Roland Garrros. Djokovic goes in and out and is incapable of maintaining the perfect level he needs to beat an in-form Rafa on the dirt because he has less margin for error on all of his groundstrokes. It's hard, though, to envision Rafa reaching his peak this year.