A great defensive basketball team is able to help on the weak side, and then recover in time and close out their own man on the catch. As the ball is in the air, the defensive player must already be on the way to close out their defender. You may choose to close out short or hard depending on what type of player it is, but the player needs to be there as the offensive player is catching the ball.
The 1 on 1 help side recovery basketball drill breaks down the help side defense, works on closing out your defender, and then playing 1 on 1 defense. This defensive basketball drill should only be used once you have already taught your players the right way to recover and close out.