You will hear this phrase said at some point: “The pitcher supplies the power.” It may even be during a major league broadcast. Is this claim really true? Or does the batter have to supply the power?
Robert Adair answers this question quite thoroughly in his book, “The Physics of Baseball“. It’s a good read if you can stomach some math and physics. The technical answer goes into how much distance will be added to a struck ball if a pitch is thrown say 1mph faster. There are conditions such as wind and humidity that of course will affect this one way or another on a given day, but those aren’t of great interest. There are properties of the ball, which do not change. The COR (coefficient of restitution) specifies how much energy of the pitched ball will be successfully retained after colliding with the bat, affecting the rebound velocity.
But when looking at the critical aspects of a struck ball, the pitch velocity, the bat velocity and mass, and the point of contact, it turns out that adding velocity to the pitch does not translate drastically into exit velocity, or power, for the batter.
So the answer is that of course the pitcher supplies some of the power, but the batter supplies the great majority. Therefore to be a successful hitter at higher levels, hitters will have to provide athletic swings that generate bat speed.
Still not convinced? The book also provides a beautiful simple way to think about this question. We basically already know the answer if we think about it for a minute. We are not surprised at all when we see a coach hit long fly balls to outfielders without an extreme amount of effort. There is no “power” being supplied to the coach. The ball has no velocity opposite the direction the coach is hitting.
On the other hand, we also intuitively know that if a batter bunts a ball it isn’t going to go very far. This is the case where the bat has little to no velocity, and therefore the only power is supplied by the pitch. We can make a pretty good guess that if a pitcher is throwing 50mph, for example, increasing the pitch to 100mph still really won’t result in the bunted ball traveling very far.