Originally Posted by ollinger
People delude themselves into thinking that being in shape has something to do with preventing wear and tear injury. For the most part, it does not. The OP has cartilage damage/loss in his knee that apparently is now worse. That doesn't happen because someone is not in sufficiently good shape. It happens because of overuse, in conjunction with a likely genetic predisposition. Getting into the best shape imaginable does not prevent those sort of severe physical problems.
There is some truth to what you are saying, however overuse with lack of muscle strength, imbalance in muscle strength and bad posture can definitely make this wear come much sooner than it should. The more even strength your muscles have the less strain there is to the joints, the muscles take more of the shock instead of your joints.
I do agree that a player could be in great shape aerobically and still have joint problems, actually a lot of the runner types are in great shape but have worn their joints out from all the running and do little if any weight training. My point is strength training not just being in good shape, there is a difference a person could be very fit aerobically and thin but still have problems because of lack of strength and muscle imbalance.