The Player Efficiency Rating (PER) is a rating system developed by John Hollinger that aims to create a summative rating of each player in the NBA. It takes into account the positive statistical contributions of a player and the negative statistical contributions of a player to create an all-in-one evaluation.
Hollinger describes the system as a "per-minute rating of a player's performance." This format allows playing time to not dominate the system and dilute the ratings of starters versus those who get less time.
Unsurprisingly, NBA leaders in PER from the 2020-2021 regular season are some of the biggest names the sport has. What is interesting is that those at the peak of the stat are forwards, which is a position group that garners less attention in the modern NBA.
Other notable players in the NBA include LeBron James, who had a 24.32 PER and Luka Doncic, who had a 25.33 PER.
There are some consistent issues that arise in relation to the metric, often brought up by data scientists. Some of the more popular issues that are addressed include weighting problems, the fact that the statistic hasn't changed since its inception and that there are issues regarding how the scientific model is implemented with PER.
Despite this, PER is one of the most popular NBA statistics for a reason. It's easy to understand, offers NBA fans a composite look at the effectiveness of players (albeit it's hard to determine how effective) and it's been around for a long time.
It's up to bettors and fantasy players alike to determine how much they value the stat and how they try to implement it, but when watching and following the NBA this year, you'll certainly see this metric around.