This is the problem with Pakistan. India used to make similar mistakes, that's why we used to always have problems in finishing off lower order and tail end batsmen. When you have your foot over the opponent, press down harder until the opponent is completely finished. Go for the kill. Kohli did this yesterday when South Africa were collapsing. He brought in Bhuvi and Bumrah earlier than normal to finish off SA's innings and set themselves up for a really small target chase.