The Anatomy of Corner 3s in the NBA: What makes them efficient, how are they generated and how can defenses respond?

Modern basketball is all about creating efficient shots, that is, shots with high payoff. This is not necessarily equivalent to creating looks with the highest probability of success. In particular, the two most efficient shots in the NBA - which are shots from the paint, i.e., extremely close to the basket, and three-point shots from the corner, i.e., at least 22 feet apart - have completely different spatial profiles when it comes to their distance from the basket. The latter also means that they are pretty much at the opposing ends of the spectrum when it comes to their probability of being made. Due to their efficiency, these are the most sought after shots from the offense, while the defense is trying to contain them. However, in order to contain them one needs to first understand what makes them efficient in the first place and how they are generated. In this study we focus on the corner three point shots and using player tracking data we show that the main factor for their efficiency - contrary to the belief from the sports mass media - is not the shorter distance to the basket compared to three-point shots above the break, but rather the fact that they are assisted at a very high rate (more than 90\%). Furthermore, we analyze the movement of the shooter and his defender and find that more than half of these shots involve a shooter anchored at the corner waiting for the kick out pass. We finally define a simplified game between the offense and defense in these situation and we find that the Nash Equilibrium supports either committing to the corner shooter or to the drive to the basket, and not lingering between the two, which is what we observed from the defenses in our dataset.