This article is a collaboration between Ben and Dylan Murphy.
Dylan is a former G League Scout with the Atlanta Hawks and Assistant Coach with the Fort Wayne Mad Ants. You can find more of his writing at The Basketball Dictionary, and can follow him on Twitter @DylanTMurphy.
Good defense is based on pattern recognition. Each individual play is unique, but actions repeat. The speed of basketball requires players to react instinctively, and the less they have to remember, the better. So coaches teach rules based on these actions: when you see a guard caught on a big man in the post, double from the baseline; when you see a shooting power forward setting a ball screen, hard show. But the automatic nature of these responses means offenses can easily project how a defense will guard plays of a specific type.
Which is exactly how Al Horford got so open on this shot:
To understand more deeply, we need to talk about pick-and-pop defense.