The two-three zone is the classic zone defense. It is based on the fundamental belief that five players can more successfully guard defined areas than they can specific players.
It’s primary goals are to force the opposition to rely on their perimeter shooting to score points, and to goad their opponents into making careless mistakes as they grow more frustrated with the zone defense facing them.
The motto of the two-three zone is: "The other team will beat itself. All we have to do is give them the chance."
The two-three zone is often used when one team feels they are at an athletic disadvantage against another team, and, to minimize this disadvantage, they try to mask their lack of athleticism through a team oriented defense, rather than an individually based, man-to-man defense.
How to Play the Two-Three Zone
Place your two guards roughly three to four feet beyond both elbows of the free-throw line. In other words, their feet should be just inside the three-point line (if the team has strong three-point shooters, then you may want to extend your guards a few more feet). However, the more compact a two-three zone can be, the more stifling opposing offenses will find it.
Place your center--or the biggest player on your front line--roughly one to two feet outside the dotted circle, in the center of the lane. Place your other two front line players above each bottom block, on both sides of the lane.
The nature of the 2-3 zone is predicated on each player understanding the necessary movements that the defense requires. In other words, each player has a designated area to defend, and a certain part of this area, depending on where the ball actually is at a given moment, becomes what we will call the “Hot” area; the area where the defender needs to be.
For example, the defenders positioned at both elbows first must realize which of them should step out a foot or two to defend the ball. This depends on which side the man handling the ball comes down the floor on. If he comes down the defenders’ left side, he is the defender on the left elbow’s responsibility. If he comes down the right side, he is the defender on the left elbow’s responsibility.
So, let’s say that the point guard comes down the left side, the man at the left elbow steps out, while the man on the right elbow slides over to the middle of the key. He remains above the free throw line, to make sure that, if the point guard tries to get into the lane off the dribble, he is there to stop him.
The defender’s presence above the foul line also ensures that nobody will be able to flash into the middle of the key from the opposite side of the floor, which is called the weak side of the floor. The center shifts slightly to the left side of the circle, ball-side, as we call it, while the man on the left block steps up a few steps.
The man on the weak-side block shifts towards the center of the lane, ensuring that the middle of the key is protected while the center has moved over. Timing on this is key; if one player is late on a rotation, the defense is helpless.
A flaw of the 2-3 zone is that if there is a breakdown in the rotation, large gaps on the floor are created. To finish the example, when the ball is passed from the left side of the floor to the right side, the defense shifts the opposite way, all the while ensuring that no penetration is allowed, and that they all are covering the necessary “Hot” areas in this given situation.