Over the seven decades the NBA has existed, a lot has changed -- including even the name of the league, which originally incorporated as the Basketball Association of America (BAA). Differences in style of play, level of competition, rules and the addition of the 3-point line make it difficult for us to compare across eras for projects like ESPN's ongoing effort to pick the best NBA players of all-time using #NBArank voting.
One thing hasn't changed: the championship trophy for which all teams are competing. (OK, technically, that too has changed styles and names, but the concept is the same.) So in seeking to rank every player in NBA history statistically, my north star was how much they helped teams win championships.
The result is a metric, championships added, that incorporates both performance during the regular season and the postseason (using Basketball-Reference.com's win shares) and gives true stars more credit for their contributions than players who merely hung around. I also came up with the idea of valuing subjective honors such as All-Star appearances, All-NBA picks and MVP voting based on how well they translate to winning championships.
For more on the details, including what I found about how performance translates to championships, I wrote up a full description. If you just want the results, read on to find out how I've ranked the 40 best players in NBA history.