The Ringer's Bill Simmons likes to refer to the 'Chemists' on NBA teams. These are bench guys who are chemistry specialists. The unsung heroes whose primary role is providing sage veteran advice, lending a keen ear, and generally keeping a team together (like Udonis Haslem).

Chemists, or the glue guys, are indespensible and can bring a team of disparate parts together to overachieve like nothing else. But you still need on-court talent, the ingredients, or chemicals, before Chemists are brought on.

This article is about one of those ingredients.

A class of players whom I will call here the 'Catalysts'. Just as catalysts in chemistry speed up a reaction without being part of it, our Catalysts turbocharge the offence, and their presence helps others to perform at their best.

You might think of a classic point guard like Chris Paul, a big man who opens up the floor like Embiid or Anthony Davis, a transcendent shooter like Curry or Lillard, or just an all around monster like LeBron who demands attention and frees up others.

Let's get started by identifying the best Catalysts for the 18-19 season. In a follow-up, I will look at the 19-20 season to date and the best Catalysts.

Identifying the Catalysts

Shot value

As modern NBA fans, we are keenly aware that some shots are better than others. To look at where efficient shots come from, the floor can be divided into distance-based zones, and average value for each zone calculated and visualised:

An average NBA shot is worth about 1.08 point per shot. So, 'good' shots in comparison to this average are those from within the restricted circle (we'll call them 'inside' shots), and 3s from under 28 feet.

So who creates these good shots not just for themselves, but for their teammates?

Inside & outside

As a starting point, let's look at which players are most adept at creating (or destroying) the two types of shots that the modern, analytics NBA is about - inside shots and corner 3s.

My guess is that approximately 0% of you are surprised to see the identity of the runaway leader in creating corner 3s and inside shots for his teammates. It's James Harden, the leader of the analytics-obsessed Rockets.

There are some surprises in this plot, like Nikola Vucevic creating a ton of both for his teammates, Lou Williams creating the most inside shots to his teammates' diet, and Enes Kanter taking shots away from both zones.

For the most part, though, the plot makes sense, and it gives you a good sense of how a player being on affects play style of the team. When a player like Harden, Curry or Luka is on, their shooting ability and attention just opens up both areas.

Some parts of the plot are just a function of the player's role. Gobert and Capella are classic big men, and play so much pick & roll as the roll man that they are going to take away other players' shots at the rim. This doesn't make them not valuable, or bad. In fact, both of these players create opportunities for others on the three point line, and have solid numbers on the offensive end, traditional and advanced.

What it probably does indicate is that these players would be best complemented by other players who can space the floor.  

(If you read that last line and thought: "hmm what about Embiid and Simmons?" - stay tuned, I am writing an entire piece dedicated to these two.)

So, let's look at a more holistic figure - at the total amount of good shots created by their presence.

Positive reactions

A list of the top Catalysts might be created by adding the changes to his teammates' shot percentages from the inside, corner 3s and regulation 3s.

The top 5 here are:

  • James Harden (14%), Nikola Vucevic (13%), Stephen Curry (12%), Lou Williams (12%) and Damian Lillard (9%)

The worst 5 are:

  • Tristan Thompson (-10%), Kevon Looney (-8%), Ed Davis (-8%), Quinn Cook (-8%) and Nerlens Noel (-7%).

It seems obvious in hindsight. Players with high gravity are going draw attention to manipulate and create space, and the teammates are going to use that space to get better shots for themselves. On the flipside, players with low gravity, or even repulsion, create empty space around them, or clog the lane without doing much with it, destroying value in shots.

In absence of tracking data, I use a combination of usage rate and true shooting percentage as a proxy for gravity. Plotted against creation of good shots, the results are as follows:

Some players stand out as outliers; so let's talk about them first. Draymond Green creates a disproportiate amount of good shots, despite a relatively low-ish shooting percentage and usage rate. This likely happens from his passing abilities, great court vision and his team's great off-ball movement. Giannis, despite having a 30+% usage rate AND a sky-high true shooting percentage (62%!), may be disadvantaged a little here because of the strong bench play by Milwalkee.

Tristan Thompson is the anti-Draymond here, where despite a reasonable usage rate & true shooting percentage, just isn't able to create space for his teammates anywhere. Thompson achieves a rare trifecta, as his teammates shoot less from  all of the inside, corner 3 and regulation 3 zones.

More importantly than a few (slight) outlers, there's a good, strong, linear relationship between our definition of gravity and good shot creation. Even these outliers don't buck the trend so much as lie off to a side of it.

To confirm our findings here, let's look at a few shot charts for these players to assess exactly how they are changing their teammates' shots.

Catalytic Reactions - by player

James Harden (Houston Rockets)

These shot charts focus on differences made to shot locations when Harden is on the floor (red) vs when he is off the floor (grey). Another way to describe it would be that Harden being on the floor means that shots that would have been taken from the grey markers would be taken from the red spots instead, darker colour indicating more shots.

Harden gets these above-the-break 3s and short range shots from the lane 3-7 feet away and converts them to corner 3s and shots right at the rim. And remember, these are his teammates' shots, not his own.

For the record, including Harden's shots really doesn't change the situation that much.

Yes, the differences are smaller at the corner, but on average attempts are much closer to the rim, and these shots from the midrange (many of them probably Chris Paul's) still go away.

Whatever you think of Harden's game, he drives that offence.

Steph Curry (Golden State Warriors)

Curry is the very definition of gravity. His being on the floor creates shots everywhere around the rim. Remember our gravity vs good shots scatter plot above? You'll see there that Steph increases the inside 4 foot shots by 10%.

That's an overall increase of 10% - as in, 10% more of all shots from each game now come from inside 4 feet when Steph is on the floor. That's an absurd number, and watching any YouTube breakdowns of the GSW offence will show you why. Defenders just lose their minds in trying to cover Curry's absurd range, and his off-ball movement and screening often get them confused, and both him and his teammates were good enough to take advantag of it.

When he's back from his hand injury, it will be really intersting to see what this looks like with fewer superstar teammates and younger team to see how they take advantage of his gravity.

Giannis Antetokounmpo (Milwaukee Bucks)

Giannis is an interesting one. He is supremely skilled, and has range in so far as he can seemingly attack the rim from anywhere, including near the 3 point line. As a result, he demands attention from anywhere even though he is not (yet) an elite shooter.

The image on the left shows changes to his teammates' shots when he is on. As a classic big man, the others' inside shots decrease, and his gravity inside increase 3s.

As a caveat, I include the shot chart on the right that includes Giannis' shots as well as his teammates' on the right. Adding his shots show that actually, the Bucks attack the rim a lot more with him on than off.

But overall, his gravity is (or was, in the 18-19 season) still quite limited in range. And the resulting changes to shot distribution for his teammates is perhaps not as positive as it could be.

Ed Davis (Brooklyn Nets)

(In extremely Zach Lowe voice) Oh boy.

We are down to the other end of the graph - look at Ed Davis' on/off shot chart here. Even when I include his own shots, the Nets are shooting from further away with him on the floor, especially in the middle (and the corners, too).

I had to look twice when I saw this. His OBPM is negative, though, and to me that speaks volumes. The Nets are just not getting good shots with him on the floor vs with him off.

Tristan Thompson (Cleveland Cavaliers)

Tristan Thompson being on the floor absolutely makes these shot charts look as suboptimal as possible, given what we know and how we think about basketball in 2019/2020.

It looks like whatver unit Thompson is on with has actively decided to seek out as many midrange shots as possible. The chart on the right, which includes Thompson, shows you that he is a happy participant in the midrange warfare. And he's not exactly Aldridge, DeRozan or Chris Paul from that range. (He shot a passable 50.6% from 3-10 feet, but then shot 39% from 10-17 feet.)

Thompson has been a solid player for a long time, and the Cavs last year were a trainwreck. It would be harsh to judge anyone from that season's data only. And yet, the data suggests that he didn't really help to make things any easier for his teammates.

Nikola Vucevic (Orlando Magic)

From looking at this chart, the value that Vucevic brings to the Magic is clear. He converts a bunch of shots from the purgatory of 10-24 feet range to rim shots, and corner 3s.

Vuce shot almost 55% from 2 point range, and a respectable 36% on threes, with almost 3 three pointers a game. His gravity as the main or second scoring option on the Magic was real, and its impact is evident on this chart.

I've heard that Vucevic is potentially criminally underrated, and after seeing these and his advanced stats it's hard for me to disagree.

(Note: the first version of this article didn't include Vuce!)

If you think the list is missing a player who should be included, let me know on twitter. I will look at it and include them on a follow-up article or personally deliver you a personal, handwritten apology.

There's much that I would still like to write about, including how players being on/off changes shot percentages from the same zones, how they change foul rates, and how all of that translate to points.

Also, I intend to look at similar data but for the defensive end - how a player affects the opponent's shot locations and accuracies. That's going to be really interesting and I look forward to doing that.

If you liked this - I'm on twitter, say hi!


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