Here is a drill that can be easily done indoors during these colder months. It’s a drill that focusses on a base runner’s starts when attempting to steal. Good base stealers get good jumps and this drill teaches and improves this very basic need for runners.
Explode to the ball!
To do the drill, have a runner get a lead as normal. A coach or partner stands about 10 feet farther down the base line and holds a tennis ball about shoulder height. When the partner/coach drops the ball, the runner explodes towards their base and tries to catch the tennis ball before it bounces twice. The height at which the ball is dropped and the distance away from the runner can vary depending on the age and skill level of the runner. As the runner gets older/better, the partner/coach can make the drill more challenging by moving farther away and/or lowering the height of the ball before dropping.
Often coaches struggle to find indoor drills for base runners during the colder months. This is a good one because all you need is two people, a tennis ball, and at least 20 feet of running space.
