Having been a catcher in my playing days, I know the need for hard accurate throws when runners steal. Unfortunately it is one accept of the game which is not practiced enough at Junior level, and I started doing this practice with my teams.

Catcher Drills for Base Stealing
Aim of the drill is to FOCUS on where the balls is to land, and to ignore what fielders and runners are doing.

Equipment required:   Minimum of 6 balls, milk crate or washing basket.

Drill — measure out the correct distance from home plate to second and third base.
Place the crate or basket where the base should be.
Have catcher adopt the squatting position and have someone toss balls to them (good use of injured players or idle parents).
Then have them throw the runner out by getting the ball in the crate.

Rotate between 2nd and 3rd to adjust for shorter distance and change of body action to throw.

Once you have spent 10 minutes watching and correcting stance and throwing technique, it is a “walk away and leave drill” and one that can be practiced anywhere all year round.