Sometimes it is not easy to be an engineer and a baseball coach.  You see and hear things that don’t makes sense — like the talk about “exit velocity” for hit balls.   Just because you CAN measure something DOES NOT mean that it is meaningful or that you should measure it.   Exit velocity is one of those things.   The velocity at which a ball comes off a bat is controlled by Newton’s laws, a function of: 1. The speed of the bat at impact 2. The mass of the bat 3. The material properties of the bat – ash, maple, metal, sweet spot, etc… 4. The speed of the ball, its rotation, its mass and material properties 5. The angle of impact and angle of ball trajectory 6, Other factors too … All of these things matter — a lot.  Click here for the discussion by Stalker Radar which talks about the angle of measurement impact on radar gun velocity.  A 30 degrees angle difference, which would still be considered a line drive, would measure 13.9% different than a line drive at 0 degrees angle from the radar gun.  That’s the difference between 80 mph exit speed and 70 mph exit speed. A fly ball or groundball at a 45 degree angle would have a 39.3% error. So, all the showcases that report exit velocity are primarily reporting whether or not a kid squared a ball up in at a 0% angle with the radar gun.  Angle has that big of an impact.  It is probably just as big of a difference as the players’ actual bat speed. Then, for consistency the exit speed measurement HAS to been done off a tee, not a moving ball, to eliminate the variability of the ball.  Exit velocity off front toss or pitched balls is not measuring anything meaningful about the player.  Too many variables unless the ball is always at the exact location, with the exact spin, trajectory and velocity. And, by the way, the balls need to be exactly the same.  Not a bucket of cage balls with worn balls.  Only brand new baseballs.  And to truly measure apples to apples, all the players needs to swing the same bat. Just because you can measure something does not mean that it is meaningful. Radar guns are great for measuring objects moving at a 0 angle to the gun.  But, using them to measure impact with all the variables listed above has no meaning. Showcase scouting reports make a big deal out of a 5 mph exit velocity difference within players.  ALL OF THIS DIFFERENCE IS WITHIN THE RANGE OF ERROR OF THE MEASUREMENT.  Showcase reports are simply reporting the players that hit the ball close to a 0 degree angle with the gun.  This is luck unless you let players take about 20 swings with the same bat and same ball and only record the balls with 0 degree angles off the tee.  Not the way it’s done though,  10 swings and out with random data reported.

Reminds me of the scene from Moneyball about the ugly girlfriend ..