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Nylon Calculus: Rockets-Jazz win probabilities, assist maps, style charts and more

By Andrew Patton

SALT LAKE CITY, UT - FEBRUARY 2: Donovan Mitchell #45 of the Utah Jazz handles the ball against the Houston Rockets on February 2, 2019 at Vivint Smart Home Arena in Salt Lake City, Utah. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and/or using this Photograph, user is consenting to the terms and conditions of the Getty Images License Agreement. Mandatory Copyright Notice: Copyright 2019 NBAE (Photo by Chris Elise/NBAE via Getty Images)
SALT LAKE CITY, UT - FEBRUARY 2: Donovan Mitchell #45 of the Utah Jazz handles the ball against the Houston Rockets on February 2, 2019 at Vivint Smart Home Arena in Salt Lake City, Utah. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and/or using this Photograph, user is consenting to the terms and conditions of the Getty Images License Agreement. Mandatory Copyright Notice: Copyright 2019 NBAE (Photo by Chris Elise/NBAE via Getty Images) /
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Previewing the first-round series between the Houston Rockets and Utah Jazz with shot charts, assist maps, offensive style charts and expected win probabilities.

Shot charts

James Harden has shot a truly unprecedented number of step back 3-pointers this year — approximately one out of every three in the entire NBA was taken by Harden. He is able to use that move to generate a high percentage shot (approximately 38 percent based on recent data) with no actions, picks, or plays.  In fact, over 50 percent of Harden’s own 3-pointers are classified as a step back by the NBA. The two shot charts show the percent of all 3s that are step backs for the NBA as a whole and then Harden specifically at locations behind the arc. Harden appears to shoot a higher proportion of step backs from the right corner and left center as opposed to the left corner and right center.

This year has really been a tale of two seasons for the Jazz. After going 9-11 in their first 20 games, the Jazz have improved to the fifth seed in the playoffs with a final record of 50-32. Much of the catalyst for their improvement in record can be attributed to the play of Donovan Mitchell, their second-year star shooting guard. In October and November, he shot approximately 43 percent overall and less than 30 percent from 3. In contrast, during March and April, he shot greater than 46 percent from the field and 45 percent from 3. Zooming out slightly further, Mitchell was +3.5 pre-All Star break and +6.9 post-All Star break. As seen in the figure below, Mitchell’s improved 3-point shooting across the court has been the primary driver of his increased offensive success.

— Andrew Patton (@anpatt7)

Offensive style chart

These charts are not meant to evaluate whether an offense is good or bad. They are designed to help illustrate how teams go about the goal of trying to put the ball in the basket. Each team’s offense is evaluated on four stylistic spectrums.

Ball movement is measured with the average touch time for each team, from the NBA’s player tracking statistics. A lower average touch time means the ball is moving from player to player more quickly.

Player movement is measured with a combination of different NBA.com tracking statistics and works out to average distance traveled per 24 seconds of offensive possession.

Pace is measured with the average length of an offensive possession from Inpredictable, a more accurate representation for how quickly a team is working than traditional pace.

Shot selection is measured with MoreyBall percentage — in this case the percentage of a team’s true shooting opportunities that came at the rim, from the free throw line, or on a 3-pointer. It’s a generalized measure but captures something about how much each team hews to the shots that are, on average, the most efficient.

No other offenses present such a sharp contrast in the first round but that’s mostly a function of the uniqueness and extremity of Houston’s style. The reliance on James Harden has proven to be an issue in the past when he’s not hitting in the postseason but their system also has a lot fewer moving parts and a lot fewer places for execution to break down. It’s a study of simplicity versus complexity.

— Ian Levy (@HickoryHigh)

Assist maps: Ricky Rubio

Utah is headlined by a pair of rising stars. But — while Donovan Mitchell may be the team’s top scorer and Rudy Gobert may be the team’s most impactful player — Ricky Rubio is still Utah’s primary creator. Rubio is leading the Jazz in assists (6.1) and time of possession (5.4 minutes) per game again this season and he’s vital to the success of the team’s offense.

Rubio is one of a dwindling number of pass-first point guards who have remained effective in the NBA. A look at all the short-range assists cluttered around the basket on Rubio’s passing-lane chart shows just how much he loves to set up dunks for his teammates with lobs and dump-offs. In fact — among all the primary creators who drive to the basket at least ten times per game (47 qualified players) — only Russell Westbrook finished a larger percentage of his drives with an assist to a teammate. Moreover, most (215 of 416, 52 percent) of Rubio’s assists this season have been converted at the rim.

In the four games that the Jazz split with the Rockets this season, the entire Houston backcourt took turns guarding Rubio, but his most frequent opponent was James Harden. During these possessions with Harden covering Rubio, the Rockets allowed the Jazz to score above their average rate. Given the alternatives (Harden guarding Mitchell or Joe Ingles), Houston is likely to run back that matchup in the playoffs anyway; it will be worth monitoring whether Harden shows any signs of fatigue after chasing Rubio around the court for a few games.

— Todd Whitehead (@CrumpledJumper)

Win probabilities

To project the series, I am using my in-season game projection model. The model is trained off historical game data and accounts for rest, travel, team strength, and matchup. Since I began using the model to predict outcomes, I have been able to correctly identify the winner in about 70 percent of games.

The Rockets come into the series as slight favorites, winning in 54 percent of the 10,000 simulations. The average length of the series was 5.8 games, with the Rockets given just over a six percent chance to sweep the series. This will be the most exciting matchup of the first round. The two teams are evenly matched with a 63 percent chance to go to six or seven games long. Whoever survives will likely face the Warriors in the next round as their reward. The ultimate test of defense versus offense, the Rockets are every so slightly more likely to move on but one wrong step by either team will lose them this series.

— Jacob Goldstein (@JacobEGoldstein)

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