This post originally appear on Nylon Calculus on 11/5/2014
On Saturday night the Boston Celtics very narrowly avoided setting a record in three point futility when Jeff Green hit the team's first three pointer after 21 misses, avoiding the 0-22 record set by the Denver Nuggets. They ended up 1-25 from three on Saturday, a game sandwiched between 36.4% and 35.5% three-point shooting performances.
Almost immediately, after the the Saturday game, the three-point skeptics came out of the woodwork. Given the immutable arithmetic of 3 > 2, the objections were more subtle and plausible than "threes don't win ringz." OK, I saw one commenter on a blog write that, not sure if it was Byron Scott or not, but to focus on that would be just be nit-picking. There were a few, potentially, valid criticisms of the Celtics' beyond-the-arc shot selection on that futile night that we can check, in part, thanks to SportVU:
- Too many threes
- Too early in the shot clock or too late in the shot clock (three point attempts are like Goldilocks, apparently)
- Too many contested threes.
So was that all true, was the shot selection process off or was is mostly a bad luck night? We can't tell from the result and I would argue it is hard to tell simply from watching as it's often very hard mentally to separate process from results. If something goes badly our natural instinct is to look for and find reasons why. If you are confident that this doesn't apply to you, then it almost certainly does.
Thanks to SportVU data at the NBA.com site, we can now perform basic checks on a good portion of those claims. Too Many The 'too many' claim is somewhat subjective. But it is easy enough to look up the NBA average and compare to the Celtics' infamous barrage. The Celtics took 25 attempts from three in Houston out of 98 total shot attempts, for a 25.5% three-point attempt rate. League average three-point attempt rate last year was 26.1%, with 23.6% for the eventual champion Spurs and 26.2% for Eastern Conference champions the Heat[1. Per Basketball Reference].
In fact, the 1-25 night was a pretty typical three-point attempt rate so far this season for the Celtics with the other two games at 25% and 30.4%. There are certainly legitimate questions about the number of threes taken, and more particularly whether the right personnel is taking them (such as Marcus Smart, who has struggled in Summer League, preseason and three regular season games from distance). But on the face of it, it is difficult to say the Celtics took too many three attempts.
Too Early or Too Late
Personally I don't have an issue with an open catch-and-shoot three in transition by a good shooter, a shot that has been trending up in the league the last few seasons. Transition threes are good shots, though immediate threes, most likely after offensive rebounds are less efficient, interestingly.
But, whether it's advisable or not, did the Celtics take a significant number of early threes while going 1-25?
According to SportVU the Celtics took 20 percent of their threes in the first six seconds of the shot clock, which would include shots after offensive rebounds, and 22 percent of their twos in that part of the shot clock. Last year for the league as a whole ~16 percent of three point attempts were taken in the first six seconds of the shot clock. But the Celtics also took more two pointers early in the clock than league average (~20%) last year in the Houston debacle, but given the number of offensive rebounding opportunities it isn't surprising that they had a few extra shots with the clock reset.
On the "Too Late" charge, in part it depends on where we decide "Late" is, NBA.com provides two late time bins, 7 to 4 seconds left and 4 to 0. If we use the more expansive version of Late it doesn't appear that the Celtics shot more threes than typical for NBA teams, but the Celtics took 16% of their threes in the less effective final four seconds. Below is the shot distributions for the Celtics infamous performance and the entire league last year:
The Celtics shot clock usage follows the league average, with only the Very Late shots off the league average. Shots in the last four seconds are less efficient, whether from two or three, 38 percent eFG from two and 44 percent eFG from three in the last four seconds of shot clock[2. Per NBA.com/Stats].
According NBA.com's Player Tracking data, 18 of the Celtics 25 threes were Open or Wide Open, for 72 percent. However, in their two more normal shooting nights against Brooklyn and Dallas, 77 percent and 87 percent of there threes were wide open. Meaning they were getting significantly more open looks, though not enough to account for the 4 percent shooting performance.
All told there evidence suggests, I think, that the Celtics near historically bad shooting night was some combination of sub-optimal process and simple bad luck, as are so many outlier events.