Nobody grades the low man and that is the problem

The third defender in a ball screen decides more possessions than the two players everyone actually watches.

Watch the replay again, but keep your eyes off the ball. Two defenders are handling the screen and a third one, standing somewhere near the weak-side block, is quietly deciding whether the whole thing works. He is the low man. He steps up to meet the roller, or he does not, and either way he leaves something open behind him.

Almost nobody grades him. Coverage gets logged as drop or switch or blitz, all of which describe the two defenders nearest the ball, and then the roller catches at the rim and the box score writes the story as a blown drop. It was not a blown drop. It was a low man who arrived a beat late from the wrong angle, and the highlight will never say so.

I think this is the most consistently misassigned blame in basketball. A big man gets a reputation for being slow in coverage over a season, and half of the clips that built the reputation involve a wing who was supposed to stunt in and stayed home on a shooter he did not need to respect. The reputation sticks to the big because the big is in frame.

There is a real reason the job is hard. The low man is asked to solve a problem with two wrong answers. Step up early and the corner shot is open, and everyone in the building knows that is the attempt the defense is trying to avoid. Stay home and the roller catches at the rim, and that is worse. So he has to sell a lie: look like he is coming, arrive only if the pass is actually thrown, get back out on a shooter who has already started rising. The best ones do it with their shoulders and their eyes rather than their feet, because feet commit.

You can coach this, and the teams that do coach it are usually the ones whose defensive numbers look better than their personnel suggests. They are not switching more cleverly. They have simply decided that the second most important defender on a ball screen is not standing anywhere near the ball.

Until somebody puts a number on that job, we will keep firing the wrong assistant coach.