Inspired by Ben Falk’s Predict challenge on his website, Cleaning the Glass, (a really cool website if you’re an NBA fan) and filled with intrigue about year 1 of the LeBron led Lakers experiment, I decided to tackle this question.
So, how should we go about answering it?
Defending the jump shot, particularly the 3-point shot, is one of those seemingly small topics that for some reason I keep coming back to. I think what first peeked my interest was a podcast in which a guest speculated that one of the biggest unanswered questions in basketball analytics was the degree of control the defense has on the offense’s 3-point field goal percentage. He said that some analysts guessed that much of the year-to-year variability in 3-point percentage defense was due to chance. The main source of control a defense has with to respect to 3-pointers could be limiting the number of attempts (particularly open and corner threes), rather than forcing a low percentage.
I dived right into some small projects inspired by this discussion. My first post examined whether the shooting ability of the players actually taking the 3-pointers against a particular defense had some ability to explain variability in 3-point percentage defense. I looked into whether the Celtics’ sustained run of top-5 3-point percentage defenses under Coach Brad Stevens could be a fluke of randomness (it’s highly likely it’s not). I also analyzed which team statistics were most likely to carry over from the first half of the regular season to the second, and found defensive 3-point percentage was low on that list.
Now, I have tried quantify exactly how many points of defensive rating (points per 100 possessions allowed) are subject to opponent shooting variability. Besides simply considering 3-pointers, I also looked at free throws and ‘deep’ 2-point attempts, where I defined deep as greater than 16 feet.
