Experience
An inexperienced player will not know what to do in certain situations (eg hog the strike with a better batsman left at the other end) and may well make stupid mistakes that a more seasoned player would not.
The benefit of experience is questionable, but I believe it gives a small boost to general performance. In BT it doesn't help the player protect the tail, rotate the strike etc or anything you'd hope it might. Maybe it will in future...