Whoever got back is the coverage you are playing

The first ball screen of a possession is defended by two players who never practiced together.

Watch the first eight seconds of any possession and count how many teams are in the coverage they actually practiced. Almost none are. The early screen in transition gets set by whoever is nearest the ball, on whoever happens to be back, and the two defenders sorting it out are often a wing and a guard who have not taken a single rehearsed repetition together in their lives.

Coaches file this under transition defense and move on. I think it is the most consequential coverage a team plays, because it happens before the matchups exist.

In the half court, everything is arranged. Your big is at the level he chose to be at, the help is on the side the scout asked for, and the call came from the bench. None of that is available when the ball is coming up the floor at speed. The man guarding the screener might be your best rim protector, or he might be a forward who has been taught exactly one thing and is now being asked to do the other thing. The two of them have about a second, no words, and a lot of noise.

So stop treating it as a call and start treating it as a rule. Two defenders, one sentence, no bench input. Whatever you decide, decide it once and let the entire roster inherit it, because the alternative is that the answer changes depending on which two players got back.

Practice makes this worse, not better. Nearly all five on five work is starters against starters, which is the one arrangement that never occurs in the moment I am describing. If it were my gym I would throw the ball off the backboard, shout two names, and make those two defend a live screen with the wrong bodies. It looks ugly. It is the only version of the situation that is honest.

The cost of getting it wrong is not the shot. It is the cross match you then carry for the rest of the trip, a guard on a big or a center chasing somebody out to the wing, and the switch you make to repair it is usually the exact switch the other team spent the timeout hoping to buy.

Your playbook covers the third screen of a possession beautifully. Nobody is guarding the first one.