Defenders are timed on how fast they leave the paint, but the game is decided by how well they stop.
Nobody grades the second half of a closeout
Slow a closeout down and count the steps. The first four are cheap. Any professional athlete can cover fifteen feet in a hurry, and every tracking system on the market will happily tell you how fast he did it. The last two steps are where the possession is actually won or lost, and almost nobody puts a number on them.
Here is the mechanism. A defender sprinting at a shooter carries momentum that has to go somewhere. If he plants late, the momentum goes forward, into the shooter, and you have given away two free throws or a drive into an empty lane. If he plants early, he arrives short, and the shot goes up clean. The window between those two failures is maybe a foot and a half of floor. Everything coaches call effort is really a braking problem.
I think that is why the best closeout defenders often look slow on film. They are not slow. They are decelerating on schedule, which reads on video as coasting. The guy who looks spectacular flying out to the arc is frequently the guy whose team gives up a layup four seconds later.
Braking is also the harder thing to teach. Acceleration responds well to strength work and to simply wanting it more. Deceleration is a coordination skill under fatigue, and fatigue is the point. Nobody blows a closeout in the first quarter. They blow it in the fourth, on the third rotation of a possession, when the legs will not take the load and the plant foot slides.
The grading systems have not caught up. Contest rates count hands up. Distance to shooter counts proximity at release. Neither of them notices that the defender arrived out of control and the shooter simply chose not to attack him. You end up rewarding recklessness because recklessness photographs well.
What would I want instead? Something simple and unglamorous. Measure how often a closeout ends with the defender still in a stance able to move laterally within one step. Call it a recovery rate. It would be noisy, it would need cleaning, and it would still tell you more than the speed traces do.
Until somebody builds that, teams are hiring for the wrong half of the action. They are paying for the sprint and living with the crash.

