I agree that conditioning your body and taking the time to prepare it for upcoming games/tournaments ect. plays a big part in the injuries, as does bad mechanics, but being a player myself i`ve, also seen alot of injuries come from just playing agressive and going after a ball that catches an unlucky bad hop, or a line drive that you just couldn`t get a glove on. I also know, having experienced it myself, that a player can recieve an injury from her/his everyday life but hold out on telling a coach about it because they fear the chance of not playing, the injury then worsens because or the wear and tear it takes during the game and becomes a major problem. Lack of communication on the field also causes a threat, many players forget that there`s eight other people on that field with them and three of them are usually going after the same ball they are, they have to talk and let each other no they`ve got it and that they need room to make the play.