This player increased his bat speed by 12-14 mph training 2x/week over 6 weeks. His initial gain, however, came from creating a longer swing so we had to focus on quickness. Each swing in this clip is the same bat speed - he difference is how the body creates the bat speed. On the left is a longer, dragging swing dominated by the arms, but more efficient rotation allows him to generate the same amount of bat speed in much less time on the right. It's also important to point out that the clip on the left comes from a full load/stride, where he is "just turning" on the right (no stride). This is a great illustration of a player learning to use his body more effectively to swing the bat.