Elbows and other arm injuries are completely understandable. No other major sport, even QB, puts the kind of strain on an arm that baseball does. Leg injuries do seem preventable to me as well, but the constant sprinting and stopping, then sprinting again, is tough. Football players are typically on their feet for 5 minutes or so at a time, then stand or sit on the sidelines for another 5 or so minutes, before returning to the field. I am not a doctor by any means, but I think our bodies are more suited to this type of exercise instead of sporadic and sudden movements surrounded by longer periods of little to no activity.