Most pitchers vary their leg kick from the stretch with a running threat on first base. Personally, I think a high kicking LHP is toughest to run on. If the runner goes on first move, he just throws behind the runner. If the runner waits until the pitcher commits to the plate, he gets a bad jump. At the youth level, it's a different story. Often the runner can startle the pitcher into a balk if he jumps at the moment of decision for a reading pitcher. Delayed steals can also be effective against sleepy middle infielders, regardless of the quality of the pitcher's move.