When you are trying to set your basketball team up to be great defensively, you first need to be able to breakdown some of the individual responsibilities, and explain to your basketball players what and how they are supposed to be playing defense. After that you can move into 3 on 3, 4 on 4, and then 5 on 5 defensive strategies.
One of the bigger responsibilities of team man to man defense, is to being able to plug the gap (help a teammate that gets beat), and then recover to close out your man if it is kicked to them. This defensive basketball drill is designed to work on that exact situation, and will give some good reps against live competition.
Drill Name: 1 on 1 Plug & Closeout Drill
Drill Goal: Work on plugging the gap and then closing out your man on the kick out.
Equipment Needed: 1 Basketball, a coach, and at least 2-3 players
Tips: Don't open your chest up to the ball when you plug the gap. You want to already be in the gap on defense and the closeout while the ball is in the air, be there on the catch. Closeout with high hands and be ready to slide laterally and cut off the offensive player.
Directions: One defender starts in the paint and then there are two offensive lines on either wing. The one wing will simulate the drive and then kick the ball to the other offensive player on the opposite wing. The defender in the middle must plug the gap on the first drive and then closeout and recover on the kick out. On the kick out the ball is now live and the players will go one on one until either the offensive players scores or the defender gets a rebound. For this drill you want to be on defense, so if you get a stop you stay on defense. The offensive line is behind the first driver and after they drive the next time they will be in the "live" line.
You can limit the number of dribbles allowed by the offensive player to make this drill more game realistic.