Four players stand in a square around the lane, two at the elbows and two on the blocks, with the fifth taking the ball out of bounds. It is an inbounds alignment first and a half-court starting shape second.
Why coaches use it
From a box, any player can screen for any other player, and the angle is already good. Elbow to block is a down screen. Block to block is a cross screen. Block to elbow is a back screen. Elbow to elbow is a flare. You can run four completely different plays out of the same four spots, and the defense sees the same picture every time until the first cut.
It is also compact. Four players standing close together means four defenders standing close together, and defenders who are that close have to communicate every screen or switch. Most teams do not, and the second screen in a box set is where they usually break.
What comes out of it
- Cross screen. The strong-side big screens across and the weak-side big cuts to the ball-side block.
- Screen the screener. The player who just set the first screen gets screened himself and dives while everybody watches the first cutter.
- Zipper. On a sideline inbounds, a player runs the lane line off an elbow screen and catches in the slot.
- Pin-down to the corner, which drags a defender out and empties the ball side.
- A safety valve. The screener pops out so there is always somewhere to throw it, which matters more than the play itself when the count is running.
Whatever you run, give the inbounder a place to throw it on the fourth count. That is what keeps a box set from becoming a five-second call.