The Launch Angle is basically the angle of the path the ball takes off of the bat. We used to call these Launch Angles things like fly balls, line drives, or ground balls. Now we can measure the angle as the ball comes off the bat.
Why is this important to know the launch angle? I think it is important for a few reasons. One is the batting tunnel deception as I call it. I can't tell you how many times I have heard a coach tell a hitter they hit the ball on the line when they hit the ball into the pitching screen 5 feet from the ground. This "looks" like a line drive in the tunnel but it is probably going to be a ground ball. To achieve a home run, it is estimated it takes a launch angle of about 25-35 degrees. In the batting tunnel, this looks like a fly ball. Of course, not all hitters are home run hitters and they should try to keep their launch angle lower but either way, the deceptive qualities of the tunnel are removed with the Rapsodo.
As will all Rapsodo metrics, we will also know the percentage of swings the hitter will pop up, ground out or hit a line drive. It is my opinion that a hitter that can't produce line drives frequently in batting practice will have a tough time doing this in games.
Please note that the Launch Angle is different from the Attack Angle. The Attack Angle is the Bat path TO the ball and contact and the Launch Angle is the path of the ball after contact. We use the Blast Device to test the Attack Angle.