Being able to score without having the basketball in your hands means that you are able to score off of cuts, screens, etc. These are usually easier baskets to get because they are within the offense, and because you will use another teammate to help you get open. For this game situation drill you are going to simulate coming up for a hand off from your big man, not getting the ball initially, and then getting it on the curl. Defenders are usually only able to guard so many actions in a row. So they may be able to guard the initial hand off action, but on the curl they will relax and this will open up a layup or dunk opportunity. Basketball drills like this one are great because they work on situation that you are going to come across during the course of a game.