To be able to gauge the line and length of a ball hurled in your direction at 140kph, and then respond, all in the space of about a quarter of a second, you need a huge amount of training.
A batsman has three pairs of options to choose from for every delivery – front foot or back, aggressive or defensive, off side or on side. Once he has made his picks, he must move his body accordingly, and since there just isn’t enough time to think about the best possible response, instincts must take over. But what we call “instincts” here are things batsmen acquire over a long period of time.