Originally Posted by Jack the Hack
As for the ATP tour, vive le beau jeu ! provided a pretty comprehensive list of the men's comeback players from the past 30 years. What is interesting is that I believe that only Agassi, Krajicek, and Muster ended up winning any Slams after such extended breaks, and those Slam wins took some time to pull of. Most of the other guys just seemed to lose some steam after being away so long. I believe Delpo has another Slam in him, but notice how long it's taken him to get back to the level where he's competitive.
cash also won a slam after his extended break, which occured early in his career (even younger than del potro or muster).
i edited my post and added the most significant performances in the main events for these players.