This set play is a simple way to get your point guard in position to run the middle pick-and-roll with a low post player. The action prior to the on-ball screen helps to move the defensive players so they can’t simply key on defending the pick-and-roll.
The offensive players set up as shown in the diagram. O1 initiates the play by passing to O4 at the top. O4 immediately reverses the basketball to O2 and cuts through to the short corner. If O4 is open on the cut, the pass can certainly be made from O2.
O1 replaces O4 at the top. O2 passes to O1.
O5 slides up the lane and sets the screen on O1’s defender. O1 and O5 can now run the pick-and-roll.
Obviously O1 has all options available; shoot, dribble-drive, drive-and-kick, and of course the pick-and-roll action with O5.