What is the purpose of the firm glove side? Why is important? How does letting your glove down effect your veloc. or control?
An unstable glove side can lead to posture issues and early shoulder rotation both of which can affect control and velocity. Three things to watch out for are dropping the glove, pulling the glove and flying open with the glove.
Firming up the glove side provides a stable base for the throwing arm to throw against. It helps create a repeatable release point which should translate into better control.
Firming up the glove side also means you’re NOT doing something that leads to early shoulder rotation. Allowing the shoulders to stay closed and rotate late buys time for the hips to fully rotate thus maximizing hip and shoulder separation and, therefore, velocity.