Does Bat Speed Equal Power in the Baseball and Softball Swing
Most batting instructors agree that there is a correlation between bat speed at contact and how far a ball travels. However, some hitting coaches believe bat speed at contact is overrated in producing power. They contend that adding bat speed after contact is important because the "bat drives through the ball." They further contend that distance the ball flies is affected by how tight the bat is gripped and the speed of the incoming pitch.
Their opinion is contradicted by two scientific studies that address ball exit speed and flight/distance. The first is an ESPN Science study that explains why bat speed is far more important than how fast the pitcher throws the ball. A video is this study is below:
The second is a Bat/Ball Collision Study that answers the question: "Does it matter how tightly you Grip the Bat?" Their conclusion is no - a loose grip will hit the ball just as far as a tight grip. It explains that the ball is in contact with the bat for about 1/2000 of a second. During this time the bat moves less than 1 inch (about 5/8 to 3/4 in.). It further concludes that the ball will have left the bat before any force at the handle reaches the impact point.
Based on these studies, we can conclude that the bat speed that really counts is that attained at (or by) contact - not after contact. Great hitters use swing mechanics that generate greater bat speed earlier in the swing than average hitters. Hitters with a lot of "pop" in their bat expend all of the bodies rotational and torque energies by contact. After contact great hitters are in a relaxed (coast) mode.
In contrast, average hitters do not create as much early bat speed before contact resulting in less power at contact. Average hitters also continue to apply pressure to the bat for 20 to 40 degrees after contact, which will not increase ball flight. Often their hardest hit balls are pulled and they have little power to the opposite field. Practicing drills that have the batter 'swing through two balls' or 'hit deflated basketballs' can only add to their problem.