The always instructive Exploring Baseball Data with R explores the optimal launch angle based on exit velocity. The higher the exit velocity, the lower angle is needed for the highest probability of a hit. A fast moving ground ball is likely to find a hole.

This reminded me of what I thought was a good discussion by Alex Rodriguez and Jessica Mendoza during the Sunday Night Baseball game. Rodriguez explained that he was taught to generate back spin, the spin that creates lift, by chopping down on the back of the ball. The current crop of launch angle aficionados generate backspin the Ted Williams way, with an upper cut swing.

Swing angles to generate backspin.

Mendoza countered that it mattered less for large players like Rodriguez, who were strong enough to hit the ball out just by making contact. In her view, launch angles helped make the smaller players more powerful. My take is that like so many things in baseball, there is more than one correct answer.