In the game of basketball, the 2-3 zone is one of the most effective and difficult defenses to run. Most people think it's simple: guards at the elbows, forwards at the blocks, and a center in the middle. However, it's far more complicated than this. Who's got the corners? Who's got the guard at the top of the key? The efficiency of the zone is based on rotation. How well the defense rotates dictates the success.
So generally, you won't have it so tightly packed as I just mentioned above, unless you're playing an awful shooting team. Normally, you'll have your two guards somewhere between the elbow and the three-point line, your forwards a few feet spread out from the block, and your center locking down the paint and the high post (when the center is at the high post, you'll need the weak side defender packing in more). In a zone, the key for the low men is
to have no one behind you.
When the ball is thrown to the wing, use the free throw line as a guideline. Anything above the free throw line is the top guard's responsibility, and anything below the free throw line becomes the low forward's responsibility.
Here's how the zone should look from a general standpoint:
Notice the spacing. The forwards aren't standing on top of the block, but instead they're a few feet out of the paint, because if the ball goes to the corner, that is the forward's responsibility.
If the ball is on the top of the zone:
Assuming they are in a two- or three-guard set, one guard will pick up the ball and the other will stay help-side, able to close out on the wing if it is passed or able to clog up the line to stop penetration.
Now note the free throw line guideline, as discussed earlier. Anything above the free throw line is the top guard's responsibility, whereas anything below is the low forward's. However, if the ball is thrown (or skipped) to the wing above the free throw line, the forward will be closer to the offense than the guard. In this case, the forward must close out on the wing, not allowing him baseline, until the guard recovers at which point the forward releases the offense to his teammate. Pretty straightforward.
If the ball is swung to the corner:
Ideally, in a zone, the corner is exactly where you want the ball to go. Many teams like to trap corners, in which case the forward and guard trap the offensive player, the help-side guard covers first pass on the wing, the center closes off the middle, and the off-side forward pretty much just covers back as your safety. Anyway, without trapping, the forward closes out on the corner, and the same-side guard should be in a position to cut off a driving lane middle, and force the ball back out. The zone is used to stop penetration and to keep the ball outside, forcing the offense into three-point bombs. The center rotates over and takes away any player at the block, the back-side guard drops to the middle, and the far-side forward slides over to the middle while watching the skip pass to the wing.
There are three ways to break the zone: get really hot from three, beat it up the floor, and hit the high post. Obviously you don't want to rely on three-point shots, because chances are, you won't shoot 70% the whole game. Additionally, there are not fastbreak opportunities on every play. So the best way for an offense to break a 2-3 zone is to get the ball into the high post. Normally, in a zone offense, this will be the team's best player. He will be able to shoot the free throw line jumper, attack the basket well, and pass well. So once the ball gets inside, he has multiple options. Most teams will have a baseline cutter as soon as the ball hits the high post or at least a flasher, and he can make that pass. He can turn and face, and then make his decision whether he wants to shoot the J, attack the basket, attack and dish, or kick it back out. Now on a one-on-one situation with this offensive player and your middleman, there's a good chance this will lead to a good shot or a foul. In the zone, you want to prevent the high post entry pass as much as possible. The center can match up with this spot, and the forwards can match up accordingly. If the pass gets into the high post, though, my recommendation is to have the closer guard immediately pressure/double the high post. This will put pressure on him to make a quick decision. There's a good chance he will attack and lose the ball, take a quick (and bad) shot, or at the very least, kick the ball back out to reset. If this happens, the zone has served its purpose.
A zone isn't designed to force turnovers. Instead, it should slow the game down and force a sub-par shooting team into taking a lot of long shots or slowing down a high-powered fastbreak offense.
I'll make another post soon with a more complicated description of a trapping zone, but thanks for taking a look at the basics!