What a stretch four changes about spacing

A power forward who shoots from behind the arc, commonly called a stretch four, solves a geometry problem. In an older alignment, two big men occupied the area near the basket. Their defenders stood there too, which meant a guard driving to the rim met three bodies in a space about fifteen feet wide. Moving one of those big men to the arc removes a defender from that space, and the drive becomes possible.

The effect is larger than one defender. A big man standing near the basket can help on a drive and recover in a step. The same man standing twenty-four feet away cannot do both. He has to choose, and the offence is designed to make that choice painful: help and the shooter is open, stay and the driver reaches the rim.

This is why the pick and pop became common. The stretch four sets the screen, the guard turns the corner, and instead of rolling to the basket the screener steps backwards behind the line. The defender who stepped out to slow the guard now has eighteen feet of empty floor to cover.

The cost shows up at the other end. Players who can shoot from distance are frequently not the players best suited to defending the rim or rebounding in traffic, and a lineup with only one genuine interior defender gives up easier shots at the basket. Teams accept the trade because three points is more than two, but the trade is real and it is why many sides change personnel for the final four minutes.

There is also a subtler cost in offensive rebounding. A forward standing at the arc when a shot goes up is twenty feet from the ball. Teams that commit to this spacing tend to rank low in second chance points and treat that as the price of the open lane.

When you watch, note where the second big man stands before the ball screen happens. If he is on the opposite block, the defence has a free helper and the driver has no room. If he is in the opposite corner, the lane is open and somebody is going to be wrong.