An Analysis of the Offense of the 2016-2017 Boston Celtic's Season
This analysis gets into the Boston Celtics' offense for the 2016-17 regular season. This was a successful season for the team, as they keep making progress since Isaiah Thomas arrived. For just the second time since 1988, the Celtics earned the first seed in the Eastern Conference. First, we’ll take a look at their offense compared to the top teams this season. Then, we’ll analyze Isaiah’s influence and how well his game is integrated in the team’s offensive flow. Finally, we’ll see a little about his teammates.
We’ll use two kinds of graph here.
- Field Goals Prediction Graph: A scatter plot of the location of shots overlaid on a heat map that shows the predicted probability. We can see the position, volume, and probability for every kind of shot at the same time. There is plenty of information in one look. In this graph, the red circles represent made shots while the blue circles represent missed ones. Every shot is represented in its relative position around the basket so the reader can check where every shot took place. Finally, the color in the background represents probability according to the bar on the right side. Colors close to red represent hot spots. That's to say, spots with a high probability of success. Colors close to blue represent cold spots where the probability of a made shot is rather low.
- Spatial Shot Distribution Graph: This shows how accurate a team/player is depending on their angle to the basket. We can see preferences and trends. In this graph, we have the probability in the vertical axis and the distance in the horizontal axis. We can see how the probability of success decreases as we go further from the basket. Angles under 90 degrees (0, 30, and 60) will represent shots from the left side while the angles over 90 degrees (120, 150, and 180) will be on the right.
Offense Compared to Top Teams
Celtics' offense has a nice balance. It's a little weak at mid-range but that’s a typical scenario in the NBA these days.
Compared to the rest of the top teams this season, Boston's offense looks pretty good. We can find three types of teams among the top offensive teams. Celtics, Warriors, and Cavs have a similar pattern (not bad company for the green team.) Spurs, Raptors, Clippers and Wizards give more importance to the mid-range offense. The Rockets are in a class of their own with an almost non-existent mid-range game.
The Influence of Isaiah Thomas
For Boston's offense, there is a difference between shooting from the right corner and the left corner. We can see in the following graph that the percentage is slightly worse in the right corner when the shot is beyond the arc.
OK, not a big deal here. However, let’s see the same model focused on Isaiah Thomas. We can see that the pattern is very similar.
While analyzing his offense, we could make a point with his 0 and 180 degree angle shots. Isaiah likes to shoot off the dribble. We can see that Thomas looks more effective playing off the ball on the left side.
Even if we compare the 30 and 150 degree angle shots, which are positions close to the corners, we can see the same trend. On the other hand, for the 60 and 120 degree angle shots, there is almost no difference. Those positions tend to be in the center of the court. In centered positions, far from the basket, the typical situation for a catch & shoot would be a driver demanding help from several defenders close to the basket, This would be to get an uncontested shot outside the paint. Isaiah is the point guard and he’s clearly the offensive reference. As such, it doesn’t seem likely that his defender would leave him alone. Therefore, we can assume that most of those shots come off the dribble or off the pick & roll.
Taking all of this into account, Isaiah feeling more comfortable playing off the ball on the left looks like a realistic possibility.
Shooting off the dribble or off the pick & roll and driving layups would be other potential possibilities. We have seen some layups because these are 0 and 180 degree angle shots on the chart. Being this close to the basket, we can see that Isiah is slightly better at finishing layups with his left hand. As for shooting off the dribble or off the pick & roll, let’s look at the following graph.
If we follow the former assumption, we can see that Thomas likes to drive to the basket and looks for treys when playing off the ball, preferably on the left side. When playing off the dribble or off the pick & roll, his mid-range game is pretty efficient but he opts for three pointers most of the time. Paying attention to the colors on the graph, we can see that Isaiah not only shoots more from the left side, but he’s slightly better there as well.
As with any other team when you have a great scorer, the Celtics have developed a kind of dependence. Let’s see how his teammates stack up. In the following figures, we are going to compare the team's offense with and without Thomas.
Their offense looks pretty solid with or without Thomas. In other words, the coaching staff did a great job of integrating his tremendous offense thanks to his versatility.
Isaiah's game is perfectly integrated into the team’s offense. That’s why, on paper, he is so difficult to contain. This is due to his flexibility as well as the solid offense of the team. If you can stop him on one aspect, the rest of the team will continue its game as usual and find him in another spot. Let’s say you try to be aggressive and force Thomas to pass the ball. The Celtics' offensive flow will keep on going until they find him on the left side.
The team's main players form a heterogeneous group following different patterns in their shooting. Together they form a pretty balanced offense (inside/outside, left/right, and a reasonable use of the mid-range game.)
As we can see in the following graphs, Horford feels way more comfortable on the right side. Recall that Isaiah is more comfortable on the left side. Taking into account Horford's outstanding ability at passing the ball, it looks like we found a pretty interesting connection in the Celtic's offensive flow.
As for the rest of starters, Bradley and Crowder share a nice balance between left and right side shooting, while Amir Johnson is more effective on the left when he shoots from the outside. Crowder’s pattern is really curious as he has established his favorite spots and is pretty consistent in looking for these areas and avoiding cold spots. Bradley’s pattern is pretty consistent all around the court.
As for the bench guys, we have Smart, who the most important player coming from the reserves. Olynyk is a great fit thanks to his mobility and outside shooting, Brown is set to become an offense reference in the near future and Gerald Green is an interesting case.
They all show a nice balance between right and left side shooting, except for Green. He is much better attacking from the left side. He plays a special role since he’s not a starter, he is not even one of the main guys from the bench. But when he finds his rhythm, he can be the go-to guy for quite a few scenarios. Horford’s offense could match nicely with him since they could cover both sides. Isaiah shouldn’t play off the ball with Green since both would be looking for the same space to shoot on the left side.
As stated before, Isaiah's game is perfectly integrated into the team’s offense. He is really difficult to contain due to his flexibility as the team's solid offense. We should pay special attention to Horford and Thomas as they match up nicely. Horford is more effective close to the basket on the right side while Thomas feels pretty comfortable on the left side.
The Boston Celtics probably lack of a reliable second weapon on the offensive end. But taking into account what we have seen in this analysis, it looks like the team and Isaiah himself are ready to integrate any kind of scorer that comes along.
I want to thank Rick Wicklin. This analysis is based on the techniques described in his article, A statistical analysis of Stephen Curry's shooting. I consider his scatter plots overlaid on heat maps a great tool. I want to thank Robert Allison as well for his article, How to graph NBA data with SAS.