Reducing the value of an NBA player to a single number is tricky for a variety of reasons, including fit and the ways teammates interact with each other. Of course, that's never stopped the league from doing just that for free agents with the most important single-number rating: their salaries.
To try to project how much free agents will be worth, I've incorporated two ratings: player win percentages, the per-minute version of my box score-based wins above replacement player (WARP) metric, and ESPN's real plus-minus. Together, the two ratings give a holistic view of player performance.
Using an aging factor, I've projected both metrics for next season and combined them to create an estimate of wins generated based on this season's playing time and each player's injury history. Then, using the development of similar players at the same age from my SCHOENE projection system, I've projected 2016-17 and 2017-18 values for a total over the next three seasons -- about the average length of a contract for top free agents.
The most important step is multiplying each of those figures by the value of a win each season, which will soon change dramatically because the NBA salary cap is going up. I estimate buying a win in free agency will cost $2.2 million this summer, $2.9 million in 2016-17 and an incredible $3.4 million in 2017-18. So the most valuable players are those who will hold their value over the next three years.
Let's take a look at how that method ranks the top 30 free agents available, including some surprising results.
No. 1 LeBron James | SF
Last team: Cleveland Cavaliers
3-year value: $156 million
2015-16 RPM: +9.0
2015-16 Win%: .732
