What are you doing if you are constantly throwing the ball high in the zone?
Could be a number of things (e.g. opening up early, posture issue, glove issue).
usually something is causing you to release the ball too early. start by trying to release the ball closer to the plate. if that doesn’t work, throw a bullpen and try to skip the ball off the plate at full speed after you are loose. we had a kid when he pitched, the catcher actually placed the glove (target) on the ground, and he would throw the low strike.
if you are consistently throwing the ball high, you need to change something.
Another way to address it is to for the 1st 10 pitches or so, every pen, have the catcher move about 2-4 feet in front of the plate. This is a good drill, to understand what you are doing get yourself filmed and see where you are mechanically, could be all the things Dusty and Roger mentioned. I know following through and finishing properly cures much.
Here’s a cue that sometimes help.
When the front foot plants (down), that back arm better be up or you are going to rush things.
I’ve had pitchers be up in the zone also because they were using a slide step which was affecting the timing of the hand break where they weren’t getting the arm up fast enough and were then rushing to the plate leaving everything up.
I suggest knee to knee like Steve advocates. Hold the runner on by changing up 1 to 3 seconds and stepping off and use a knee to knee. I’m not an advocate of the slide step due to seeing what it can do to timing.