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February 28, 2016

A statistical breakdown of Ish Smith's impact on the Sixers

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For the first time since the Andre Iguodala era, the Sixers have stumbled upon a player exciting enough to win back the attention of the City of Brotherly Love. Ish Smith, an undrafted point guard out of Wake Forest, has restored life to Philadelphia basketball. But how large has Smith’s impact on the Sixers actually been?

To answer this question, I will be using data from a statistical model developed by my colleague Bryan Nelson of the University of Pittsburgh. In short, the model produces ratings for all teams in a given sport throughout the course of a season.

Approximately two-thirds of teams will have ratings between -1 and 1; 95 percent will be rated between -2 and 2; and only the best and worst teams of all time will approach ratings of 3 and -3. The model then uses those ratings to simulate the season 100,000 times in just minutes. A full description of the model can be found here.

This season, Smith re-signed with Philadelphia after the team’s 31st game. Before his acquisition though, the 76ers were bad. Really bad. According to the model, at the beginning of the season Philadelphia had a rating of ‑2.25. In relative terms, this means that Philadelphia’s performance at the beginning of the season was worse than approximately 98.8 percent of all other teams in NBA history.

In fact, the Sixers played so poorly at the beginning of the season that they hit a season low rating of ‑2.44 after their 113-88 loss to the Charlotte Hornets on Nov. 20. Few teams in NBA history have ever played so atrociously. Furthermore, the 76ers never exceeded a rating of ‑1.95, achieved the day after a 107-100 loss to the Cleveland Cavaliers on Nov. 2.

In comparison, if we observe and simulate Smith’s current stint with the 76ers as independent from the team's first 31 games, we can obtain a firm understanding of how it played during that specific stretch of time. Philadelphia begins this independent stretch with a rating of -1.59. While this still ranks them below 94.4 percent of all teams in NBA history, it is still a drastic in-season improvement from the 98.8 percent discussed above.

Moreover, the Sixers' lowest rating during this stretch was ‑1.98, which is almost equivalent to their highest rating during their first 31 games.

To get an idea of how many wins Smith has contributed to the team, we can also extrapolate the data from the Sixers’ first 31 games over the entire season as if he were never there. In this simulation, Philadelphia was expected to win only 11.69 games on average. 

However, when we extrapolated the data from each of Philadelphia’s games this year over an entire season, we found that the Sixers would have been expected to win 14.79 games, an increase of 3.1 wins.

This means that barring other potential sources of variation (other roster moves, injuries, etc.), Smith has contributed 3.1 wins to Philadelphia over the 26 games he’s participated in. Extrapolate that over an entire season, and Smith would earn the Sixers approximately 9.78 wins more than they would have had without him.

However, this still doesn’t account for the fact that a young team like the Sixers is likely to improve collectively as a season continues. To negate this, we can look at the impact Smith has had on key individual players. Before Smith’s first game with Philadelphia, Nerlens Noel’s sophomore season looked like a lost cause. Averaging 9.8 PPG on 45.1 percent shooting with 7.8 rebounds per game and 1.0 blocks per game, rumors even began to stir that GM Sam Hinkie had placed him on the trading block.

Then on Feb. 15th, the 76ers Facebook page posted this graphic about the former 6th overall pick. Since December 26th (the graphic was a few games outdated), Noel had averaged 11.8 points on 62.4 shooting percentage and 8.4 rebounds and 2.2 blocks per game. What the graphic failed to mention, though, is that Smith’s first game was actually on – that’s right – Dec. 26th.

Similarly, Smith’s arrival has had a significant impact on Jahlil Okafor. Before Dec. 26th, Okafor was averaging 17.5 points per game on 45.7 percent shooting while playing 32.2 minutes per game. Since Smith’s arrival, Okafor’s scoring has dropped to 16.9 PPG, but his playing time has also been cut down to 27.2 MPG, likely due to Noel’s improved play.

This yields a scoring rate of .621 points per minute, compared to the .547 PPM he posted before Smith’s arrival. Most notably though, Okafor’s shooting percentage has risen to 57.2 since Dec. 26th.

Smith’s impact on the 76ers this season has been exceptional. Prior to his arrival, the Sixers had won just one out of 31 games (.032 percent). Since his arrival, Philadelphia has won 7 of 26 games (.269 percent) – obviously not great, but significantly better.