It is extremely important to progress your Y's to sport specific positions! It's going to get easy performing correct Y's standing and laying prone. We want to mimic the positions and demands that sports force onto the human body. So what do we do for the baseball pitcher?
Baseball pitchers typically injure their shoulder during a throw. There are a lot of variables to take into account. The shoulder is typically not to blame. However, it would make sense to mimic the end position of a baseball pitch to strengthen the shoulder as much as possible. Take a right-handed pitcher for instance - left leg planted for balance, right leg extended fully, torso forward, and the right arm is finishing the pitch. It is essential to find any weak ranges of the shoulder, and to train the shoulder for endurance in those challenging ranges. The first exercise is a nice place to start prior to getting into standing, single leg balance finished position of throwing as you see later in the video!
Be sure to listen to the video in terms of progressing and regressing balance. However, this body position would also be excellent for 90/90 eccentric external rotation, cross body eccentric reaches, and more.