One of the more deceptive stats on the NBA leaderboard is assists. Now, obviously, an assist is always an assist, but what’s misleading about them is that they only show up when there’s a positive result. There’s no “missed assist” to counterbalance assists.
When we’re looking at scoring, we don’t just look at the point totals; we also view the misses. But when we look at assists, we don’t consider the effects of the misses, only the makes. Furthermore, when we’re viewing made field goals, we evaluate where they came. We know that long twos aren’t good shots, so we denounce guys who take shots from there. But what about table-setters who focus their attention there?
When we look at the assist leaderboard, all we see is effectively who made the most field goals. It doesn’t account for threes, for shots in the restricted area or from mid-range and long two. So here are two questions worth asking:
- Is there a noticeable difference between passers?
- Does it matter?
Thanks to the SportVU tracking data at NBA.com, we can see more details behind the assists. One thing we can see is where the assists come from. I divided the shots resulting from the passes into three basic zones: the restricted area, the three-point area and the area between the semi-circles.
There’s a reason for that. An average shot in the restricted area was worth 1.20 points. One from behind the arc was worth 1.05 points. Those in between were worth .79 points. Ergo, the same logic that applies to shooting from there should apply to setting up players there.
Here’s what the distinction looked like. The top chart shows how the league’s passing leaders distributed their dimes. The columns indicate how many points per game are scored from these players’ assists.
The bottom chart shows how the percentage of the assists in the optimal zones (the restricted area and three) compare to the total assists.
The higher a player appears, the greater percentage of his assists were optimal; the further to the right, the more assists he had.
Hover over a player on either chart to highlight him on both and display relevant data:
Notice players like Chris Paul and John Wall had significantly more dimes, but James Harden and LeBron James were much more likely to feed their teammates in the optimal zones. So that resolves the first question, but what of the second? Does it matter? SportVU also tracks what they call “assist opportunities,” which are shots attempted off a player’s passes. By looking at assisted points per assist opportunity, we can evaluate how effective a passer is when he’s setting up his teammates for shots. We can also compare that effectiveness to the percentage of his assists that are to the optimal zones:
Here we can see that there’s a relationship between passing to the optimal zones and points per assist opportunity, though, it’s always important in these discussions to distinguish between correlation and causation. There are other factors, such as team system and teammates.
That said there seems to be something of an argument for being a “smart assister” and a “volume assister.” Paul, for example, seems to be generating his assists off just more opportunities, while James is getting the most out of his passes to shooters. He’s far more likely to set up his teammates in an efficient part of the court and gets more points off his assist opportunities as a result.
I wonder if he has a twin brother LeCrause who works for State Farm.