Rotation occurs after the front foot has planted and the weight has stopped shifting forward.
Therefore, the head and eyes are in the best position to track the ball to contact. This will result in increased accuracy and consistency in the swing. The importance of this absolute rest in the fact that the less the head moves the greater the chance of sweet spot contact. Also, when the hips are rotated correctly, in the proper sequence and at the correct time greater bat velocity will result. This is difficult to do during live BP or in game situations.