It's difficult to age gracefully in general, but especially so when you are involved in a largely physical vocation. Most of us don't have this problem. We spend our 20's learning and gaining experience. We spend our 30's establishing our reputation and staking out our area of expertise. It's not until we reach our 40's, even our 50's, that we peak. We reach that perfect combination of skill, talent, and experience, that allows us to excel for a solid 10-20 year period.
Athletes have a very different timeframe. Athletes are expected to learn and gain experience in their teens. They are expected to establish their reputation and area of expertise by 22, maybe 23. They generally peak between the ages of 24 and 29, and that peak can be made even shorter by injury. Imagine being 30 years old and already in decline...
Keith Andrews is now 34 years old. But when he steps on the pitch, he still pictures himself as the same player he was ten years ago, or even five years ago. He sees a ball being played and thinks "I can reach that." He sees an opposing player attacking and thinks "I can make that tackle." He uses that skill and experience inside his head and knows exactly where to be and what to do. But his body will not take him there.
Some players make the adjustments and continue to thrive into their 30's. Some don't make any change and wash out of the game quickly and unceremoniously. Others go halfway, making some allowances, but never enough to reach their previous highs. A few spend a season or two (or five) in the wilderness, but finally figure it out.
Fernando Hierro was a world class defender at Real Madrid, one of the best the game has ever seen. But by the time he reached Bolton Wanderers his legs were gone. Hierro used his guile, his class, and his incredible technical ability to get by. And get by is an understatement. For a half of a season, for 60 minutes a match, the magic returned. But it took two very difficult seasons in Madrid, and a year in Qatar, for Hierro to reach that point. And it took Sam Allardyce to realize that the former Spain international still had something left, and know how to get it out of him. That is the other variable, the one that is out of the player's control. There has to be a manager who realizes what is happening, and who understands that he cannot ask a 35-year-old to do what he did at 25.
Gary Speed made the adjustments, and had a glorious second act in his 30's for Bolton Wanderers. But even Speedo couldn't outrun Father Time. He went searching or other clubs when he could no longer cut it at Bolton, and I suspect he never truly believed that he couldn't cut it.
Keith Andrews does not have the talent of a Hierro or a Speed, but through hard work and dedication he has managed to carve out a very nice career for himself. He may even still have something to offer in a limited role. The question is, can his mind, where he is still 25, accept a limited role?