I think he underachieved Grand Slam wise. He was such a great player on clay but he only made it past the 4th round at Roland Garros 3 times like you mentioned which is amazing. He did lose to a some great players like Courier, Guga, Stich but still.
Injuries didn't help his cause. Nor did learning to flatten out his shots so late in his career. He had trouble against attacking players but got better near the end of his career which showed with good hard court results. I think the last tourny he won was in Miami and not on clay.
To sum it up, he was a great claycourt player who won a lot of little tournaments, some big ones on clay and underachieved at Roland Garros. I don't think he underachieved overall because there were some great players he had to contend with in his prime that were better than him. When he was beginning, Lendl was there. As he matured, Edberg, Becker, Agassi, and Sampras had more talent. Near his prime, Courier played extremely well.
He was a pleasure to watch though, not because his game was beautiful, but because of the intensity and the determination he played with.
Injuries didn't help his cause. Nor did learning to flatten out his shots so late in his career. He had trouble against attacking players but got better near the end of his career which showed with good hard court results. I think the last tourny he won was in Miami and not on clay.
To sum it up, he was a great claycourt player who won a lot of little tournaments, some big ones on clay and underachieved at Roland Garros. I don't think he underachieved overall because there were some great players he had to contend with in his prime that were better than him. When he was beginning, Lendl was there. As he matured, Edberg, Becker, Agassi, and Sampras had more talent. Near his prime, Courier played extremely well.
He was a pleasure to watch though, not because his game was beautiful, but because of the intensity and the determination he played with.