Soccer players look like they retire early compare to players in the other sports, but given the dynamics of soccer, it is the right age. A soccer player will retire at the age of 33 or so (except the goalkeepers) because at that age the level of performance drops drastically and its hard for a such a player to compete with players who are in their 20's.
The soccer player Lionel Messi made headlines when he announced that he would retire. This news came not long after Messi had failed a penalty shot in the Argentina v. Chile game in the Copa America final. Messi recognized this terrible play as an indication that his career is coming to a close, so he's planning to retire at just the right time.
It does seem as if soccer players retire earlier than players in many other sports. However, there are good reasons for this. Soccer is a very physically demanding sport. You really need to be in absolutely top physical condition, or you won't be able to compete. In baseball, for example, it's easier to compete at an older age, because it's a less demanding sport.
Soccer players do not retire too early, every profession or career has an end point. It is true, that some top twenty soccer players did retire early, however it seems to be a wise decision, since most players suffers several injuries, which if not heeded to, would affect their overall health and general well being as they age.