LHP pick of ffirst

Do LHP bring the leg(knee) up in the stretch while holding a runner on first? I would think he can because the runner cant move until the pitcher strides out. But I see Kershaw without a leg kick (one time as I dont watch a lot of baseball). I would think especially he can have a leg kick since he pauses as the the foot comes down. Thanks for the info

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.