Will Carroll, BP's staff writer focusing on team health had this very interesting recent quote, from his "Cubs Team Health Report":
Age is a poor predictor of injuries. Younger players get hurt more, but they heal more quickly. Older players get hurt less, a variant of the survivor effect, but heal more slowly.
The media that follows baseball does it's best to understand and decipher sports injuries. It's a tough job for them and much gets lost in translation of medical terminology. Injured athletes often don't understand what they are being told about an injury or they are just afraid to fess up that their ache might be a significant problem until it goes on for weeks or longer. Trainers and medical staff are often reluctant to discuss information on the grounds of patient-physician confidentiality and some teams are just less open to giving what information they have to the media. The information is important to us fans, since key players dealing with even minor injuries and not performing to their best ability can drastically affect how a team plays. In 2009, Alphonso Soriano apparently had a knee injury that he tried to work through until it was so obvious that he couldn't run, leading to his arthroscopic knee surgery in September. An injury that flies under the radar screen of the medical staff, as in Soriano's case was costly and not in a way you can put the usual "days lost" analysis to.