One on one basketball drills are a great way to evaluate your players weaknesses and strengths because there is no help and the spotlight is on those two players. The one on one wing closeout basketball drill allows you to work on individual man to man defense as well as the different offensive basketball moves the players have been working on. The competition aspect of it will also show you which players really want to compete in a game situation.
Make sure that as this defensive basketball drill gets going and players start getting competitive, that you still really lock in and focus on the fundamentals of a good closeout, being in defensive stance, etc. Hold all of your player accountable. You don't want to be practicing any bad habits that are going to carry over to a game.