He had enough spin and enough game to win the French in my opinion but the stamina was definitely a major factor because of his illness. The man did win the Italian Open and he was 4-0 on clay in the Davis Cup defeating top players like Chesnokov, Kafelnikov among others. In the Davis Cup Sampras wouldn't have to worry about the long clay rallies followed by many matches over a short period of time. The most singles he would have to play is two singles matches. Not really a major strain on his body. I was thinking of natural serve and volleyers who have won the French. Edberg came close in 1989 but lost to Chang. Laver of course won it and Emerson did but that was in the amateurs and Tony Roche won it also in the amateurs. Roche and Emerson were about as natural as you can get as serve and volleyers. Rosewall could serve and volley but he was a super duper baseliner. I'm not sure if you can say Panatta was a natural serve and volleyer but he seemed to win it in 1976 that way. Noah in 1983 served and volleyed his way to the title over Wilander but I really don't think of him as a great nor a natural serve and volleyer. I would think that Sampras could have played it like Panatta.