RealGM

BPM vs. RPM, revisited, again

We were fairly pleased with how our CARMELO player projections performed last year, with the system identifying breakout stars such as Giannis Antetokounmpo, Nikola Jokic and Rudy Gobert. But we also use CARMELO to make team projections, and we weren’t all that happy with those. In fact, according to the APBRmetrics message board, which tracks various projection systems, CARMELO went from having some of the most accurate team forecasts in its debut season in 2015-16 to some of the least accurate last year. What happened?

In 2015-16, our projections were based on a combination of Real Plus-Minus (RPM), a system that rates each player primarily based on how his team performs when that player is on or off the court, and Box Plus/Minus (BPM), a system that rates players using traditional box-score statistics such as assists and steals. Last year, we switched to using BPM only. Why? There are a lot of things to like about BPM, including that it’s considerably more transparent than RPM, and it can be calculated going back several decades, making for easier historical comparisons.

But as a predictive tool, BPM does not appear to be as accurate as RPM. Instead, BPM has trouble picking up on factors such as defense and team cohesion. That led CARMELO to overrate teams such as the Minnesota Timberwolves and underrate more defensive teams such as the San Antonio Spurs last year. If we’d run the numbers using RPM instead of BPM in 2016-17, our projections would have been above-average again as compared with the projection systems that APBRmetrics tracks, we discovered.

floppymoose wrote:538 posted this:

https://hashtagbasketball.com/fantasy-basketball-projections

BPM vs. RPM, revisited, again

We were fairly pleased with how our CARMELO player projections performed last year, with the system identifying breakout stars such as Giannis Antetokounmpo, Nikola Jokic and Rudy Gobert. But we also use CARMELO to make team projections, and we weren’t all that happy with those. In fact, according to the APBRmetrics message board, which tracks various projection systems, CARMELO went from having some of the most accurate team forecasts in its debut season in 2015-16 to some of the least accurate last year. What happened?

In 2015-16, our projections were based on a combination of Real Plus-Minus (RPM), a system that rates each player primarily based on how his team performs when that player is on or off the court, and Box Plus/Minus (BPM), a system that rates players using traditional box-score statistics such as assists and steals. Last year, we switched to using BPM only. Why? There are a lot of things to like about BPM, including that it’s considerably more transparent than RPM, and it can be calculated going back several decades, making for easier historical comparisons.

But as a predictive tool, BPM does not appear to be as accurate as RPM. Instead, BPM has trouble picking up on factors such as defense and team cohesion. That led CARMELO to overrate teams such as the Minnesota Timberwolves and underrate more defensive teams such as the San Antonio Spurs last year. If we’d run the numbers using RPM instead of BPM in 2016-17, our projections would have been above-average again as compared with the projection systems that APBRmetrics tracks, we discovered.

Well duh. I've never understood their fascination with BPM anyway.