Alex Egol – RSAC Writer
DeMar DeRozan being traded to the Spurs taught us that, in the NBA, loyalty is just a word. Kawhi’s move to Toronto, along with Tony Parker’s to Charlotte, officially marked the end of the Spurs dynasty. July 18, 2018 was a sad day for NBA fans and players. In this article, we will find out whether the pain caused by the Spurs-Raptors trade was worth it for either team.
The San Antonio Spurs are 8-9 since receiving DeMar DeRozan, Jakob Poeltl and a protected 2019 first-round pick. The Raptors, who now have Kawhi Leonard and Danny Green, are 15-4. It would be bad sports analytics to use these 2018-19 team records to analyze the trade. The two new players on each team haven’t had a major impact on their teams’ records from 2017, and the small quantity of games played leaves us with a lot of unknowns for how the year will pan out. Check out http://www.espn.com/nba/team/schedule/_/name/sa/season/2018 http://www.espn.com/nba/team/schedule/_/name/tor/season/2018 for more on the 2017-18 season.
Instead, we are going to use win share statistics from Basketball Reference. Look at https://www.basketball-reference.com/about/ws.html for more about how Basketball Reference calculates their WS (WS stands for Win Shares). For context, James Harden, Karl-Anthony Towns, and LeBron James lead the league in Win Shares in 2017-18. DeMar DeRozan was 14th. Win Share will help us quantify the value of each player (and pick) involved in the trade through the games played so far this 2018-19 season.
So far, Kawhi Leonard has 1.7 win shares, Danny Green has 1.2 win shares, DeMar DeRozan has 1.8 win shares, and Jakob Poeltl has 0.5 win shares. If we use WS/48 to make sure the minutes played by each player won’t throw off our estimate, we find that Leonard produces .193 WS/48, Green produces .109 WS/48, DeRozan produces .142 WS/48, and Poeltl produces .164 WS/48. The average NBA player produces approximately .100 WS/48, or .1 WS per game. I think WS/48 enhances the value of players who play few minutes, but we will use WS/48 if we want to evaluate how much better a given player is than average.
The best way to calculate the net value provided by the package given to each team is to compare the WS received – WS traded away. Let’s look at the Raptors. Kawhi has produced 1.7 WS in 13 games. Danny Green has produced 1.2 in 19 games. If we project that for the whole season, we find that the Raptors received 15.9 win shares. To find WS traded away, we would have to find 2017-18 win shares for then-Raptors DeRozan and Poeltl. DeRozan would have had 9.8 win shares in 2017-18 if he played all 82 games (he played 80). Poeltl played all 82 games and had 5.6 win shares. That adds up to 15.4. The Raptors gained 0.5 win shares in the trade.
We will now calculate WS received and WS traded away for the Spurs. Jakob Poeltl has produced 0.5 win shares in 13 games. There are a few factors affecting Poeltl’s play: his ankle injury, Pau Gasol’s injury, and the difficulty of the Spurs’ system. Right now, Poeltl is producing 56% of the Win Shares he did in 2017-18. I think that the best way to account for these factors is to assume that Poeltl will produce win shares at the rate he is now for about half of the season, but will reach his 2017-18 level in the second half. We can project Poeltl to produce about 4.4 win shares in 2018. DeRozan has produced 1.8 win shares in 17 games. We can project that the Spurs received 13.1 win shares.
We will now move on to Win share traded away. Kawhi Leonard did not play in 2017-18, so instead we will use his 2016-17 stats. Kawhi would have produced 15 win shares if he had played all 82 games in 2016. In all 82 games in 2017-18, Danny Green would have produced 3.4 win shares. So far, the Spurs have traded away 18.4 win shares, and received 13.1.
We have not yet factored in the pick that the Spurs received. It is a top-20 protected pick, meaning that the Raptors get the pick back if it falls in the top 20. Right now, it is projected to be the 29th pick. Using this information, we will assume that the Spurs are receiving the win share of the average 29th draft pick. Below is a table containing rookie win share stats for the last five 29th picks to play NBA basketball in their rookie year.
29th pick Win Shares. Basketball Reference.
Therefore, the Spurs traded away 18.4 win shares, and received 13.1 + 0.74, or 13.84 win shares. We approximate that the trade lost the Spurs about 4.5 win shares.
This doesn’t mean that the Spurs lost the trade, though. Remember, prior to the Raptors trade, Kawhi Leonard told the organization he wanted to be traded to the Lakers. Let’s play out a scenario in which Kawhi signs with the Lakers in the 2019 offseason.
We will assume that all other players involved in the trade play on their respective teams under contract until 2020-2021. This means that, in the trade, the Raptors would have received 3 years of Danny Green win shares and 1 year of Kawhi Leonard win shares, or 26.2 win shares. We will create our own statistic called Net Win Shares (NWS), which is a measure of how many win shares a scenario creates over 3 years. The “Kawhi to LA” scenario has a NWS of -20; with Poeltl and DeRozan, the Raptors would have had 46.2 win shares of value for 3 years, but, in this scenario, they have 26.2. The alternative scenario is Kawhi stays in Toronto. The “Kawhi to TOR” scenario has a NWS of +1.5. I based this off of our earlier analysis that the Raptors won 0.5 win shares this year from the trade, and projected that over 3 years. Below is an inequality, where x = probability of “Kawhi to LA”.
1.5(1-x) – 20x ≥ 0
The left side is equal to zero, or the two scenarios work out equally well for Toronto, when x is 6.97%. For the trade to be successful for them, the Raptors must have had 93.03% or more confidence that Kawhi would resign with them after the 2018 year. That is a steep climb for a player who openly stated interest in a Lakers team that has lots of cap room.
We will create a similar Spurs inequality. The “Kawhi to LA” scenario means the Spurs have Kawhi for 1 year and Danny Green for 3. We will make a new “Kawhi to SA” scenario, where the Spurs have Kawhi for 3 years and Danny Green for 3. The Win shares received are 25.2 for “Kawhi to LA”, and 55.2 for “Kawhi to SA”. In this example, the baseline represents the real-life trade scenario, which produces 40.04 win shares. Therefore, the NWS value for “Kawhi to LA” is -14.84, and +15.16 for “Kawhi to SA”. The variable x is the probability Kawhi would have left for Los Angeles in 2019 had he not been traded to Toronto. The Spurs’ inequality is written below.
15.16(1-x) – 14.84(x) ≥ 0
If we set the right side of the inequality equal to the NWS the Spurs received in the trade, 0, we find that the two sides are equal when x is 50.5%. An x-value of more than .505 hurts the Spurs. Kawhi’s public statements about wanting a trade to L.A., L.A.’s projected cap space in 2019, and LeBron James’ arrival all make it seem like Kawhi was headed there from San Antonio. Therefore, if we assume Kawhi’s likelihood of going to L.A. was more than 50.5%, then the Spurs actually gained long-term value in the trade.
Our analysis is thought-provoking, but it’s not necessarily conclusive nor completely effective. We based multiple seasons of Win Share on a sample of less than 20 games. Also, the season is still only a month old, meaning there is plenty of time for these new players to change their play. Additionally, we have ignored factors like coachability, team chemistry, and morale in our trade analysis. Perhaps the Spurs thought Kawhi was hurting the locker room and believed that trading him would lift the play of other Spurs players, or maybe the Raptors determined that DeMar DeRozan was talented, but not a natural leader or winner. There’s no answer to these questions in analytics.
In summary, the Raptors have benefited slightly from the trade. Kawhi and Danny Green have contributed well to the Raptors’ wins so far this year. On the other side, the Spurs lost a couple of important players, and replaced them with less effective ones, but we believe that the Spurs were likely to lose Kawhi no matter what, with nothing in return. The Spurs appear to have done what was best for their future given the circumstances they were under. We conclude that the Spurs-Raptors trade was beneficial for both teams involved.