While Philadelphia Phillies outfielder Delmon Young has yet to live up to his prospect hype, he is still just 27 years old. Theoretically, he should be headed into the prime of his career. But baseball has seen a number of other players struggle early in their careers, only to develop into productive players at a later age. Raul Ibanez didn't have his first productive season until age 29. Ben Zobrist turned into an effective player at age 27, seemingly out of nowhere. Garrett Jones came on the scene at 28, the same age Nelson Cruz was when he finally started hitting big league pitching. In each case, previously unproductive players turned into far more than they looked like earlier in their careers, and they should stand as a reason for optimism regarding Young's future.
However, in each of those cases, the players hadn't really failed at the major league level in any kind of extended trial. They were minor-league lifers, tagged with the 4A label, and they spent their early twenties just trying to earn a shot at the majors. Rather than comparing Young to guys who simply didn't get a chance to show what they could do earlier in their careers, I wanted to see if I could find some examples players who had accumulated significant major league careers, and after struggling at the highest level, eventually bloomed into good players as they got into their peak seasons.